A Prominence eruption on 29 July 2004 and its consequences in the interplanetary medium
poster
In this paper we study a west limb flare/CME event occurred on 29 July 2004 in the vicinity of active regions NOAA 10652 and 10653. Although the intensity of the flare associated with the halo CME was rather low (about C2 classification), the development and ejection of the prominence associated with this flare led to a fast halo CME of speed ~1200 km/s. The development of the prominence and the initiation characteristics of the CME inferred using H-alpha, extreme ultra violet imaging (EUV) and radio measurements show interesting phenomena in the near-Sun region. For example, in association with the eruption of prominence, an intense broad burst along the time axis (width > 30 minutes of time) was observed in the frequency range of 200 to 5 MHz. In the interplanetary medium, the above event showed intense wave propagation observed at frequencies below 1 MHz. The waves obtained in the low frequency nicely compared with the flux rope propagation in the inner heliosphere as shown by IPS measurements. The radial profile of the CME from Sun to 1 AU is compared with other interplanetary and in-situ data.
2
A. Satya Narayanan
Indian Institute of Astrophysics
Fast MHD Kink Waves in the Structured Uniform Coronal Loops With Steady Flows: Heating by Viscous and Thermal dissipations
poster
The effect of steady-flows on the spatial profiles of velocities and collisional heating rates duernto viscosity and thermal conductivity of the fast MHD kink waves for surface and body modes is rnexamined in the uniform structured coronal loops under the consideration of both field-alignedrnand oblique propagations. Only body waves exist for the field-aligned propagation showing incompressiblerncharacteristics. However, surface waves are also present along with body waves forrnoblique propagation, however, existence of the obliquely propagating body waves are possiblernwhen it propagates very close to 90$^circ$ i.e., almost lateral to the background magnetic field, but not equal to 90$^circ$. Unlike field-aligned body waves, the behaviour of obliquely propagating body wavesrnare compressible. We find that obliquely propagating surface and field-aligned propagating bodyrnwaves are insufficient to heat the coronal loops. However, the high frequency obliquely propagatingrnbody waves dissipated by ion-compressive viscosity may provide sufficient heating tornbalance the coronal radiative losses provided the amplitudes of the waves are of the order ofrnnon-thermal broadening measurements or of the order of recently observed amplitude ~ 37 $pm$ 7rnkm/s by SOT/Hinode.
3
A.Shanmugaraju
Arul Anandar College, Karumathur
Transit time of CMEs under different ambient solar wind conditions
poster
The speed of the Coronal Mass Ejections at various distance from the Sun, V(R) is modeled using the equation of motion adrag = gamma (v – w), where v and w are the speeds of CME and solar wind, respectively. gamma = (alpha) R^(beta) is the drag coefficient, alpha and beta are constants. By varying the values of alpha and beta, we can get an idea about the drag coefficient. The transit time of the CME to reach the Earth is determined. We can see that, when the initial speed is high, the CME takes less time to reach earth. When alpha increases the transit time decreases, and when beta increases the transit time of CME increases.
4
Abhinav Agrawal
Birla Insitute of Technology and Science
Determination of Coronal Rotation from XBPs Observed with Hinode/XRT
poster
Abstract will be submitted by Dr. R. Kariyappa from Indian Insitute of Astrophysics, Bangalore
5
Amareswari
Indian Institute of Astrophysics, Kodaikanal
None
poster
none
6
Anand D. Joshi
Udaipur Solar Observatory
Three-Dimensional Kinematics of Two Eruptive Prominences
oral
Two large northern polar crown prominences, on 2010 April 13 and 2010 August 1, are analysed using observations from Extreme UltraViolet Imager (EUVI) on the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Both the prominences show pronounced helical twist in their legs during eruption. A stereoscopic reconstruction technique, developed by us, is used to determine the sense of twist in the prominences by observing changes in latitude and longitude of several features along the prominence legs. Changes in latitude during the eruptive phase indicate that the prominences undergo a non-radial equatorward propagation in this phase. True heights of the prominences reveal two phases of eruption: the slow rise and the fast eruptive phase, with constant values of acceleration during both the phases for each reconstructed feature. We propose that the difference in acceleration of the features along the two legs of the prominences in the fast eruptive phase is because of an interplay between the two motions viz, helical twist and non-radial propagation.
7
Ananthakrishnan, S.
NCRA
8
Andrew Hillier
Kwasan and Hida Observatories, Kyoto University
MHD Simulations of Quiescent Prominence Upflows in the Kippenhahn-Schluter Prominence Model
oral
The launch of SOT on the Hinode satellite, with it's previously unprecedented high resolution, high cadence images of solar prominences, led to the discovery of small scale, highly dynamic flows in quiescent prominences. Berger et al. (2008) reported dark upflows that propagated from the base of the prominence through a height of approximately $10$ Mm before ballooning into the familiar mushroom shape often associated with the Rayleigh-Taylor instability. Whether such phenomena can be driven by instabilities and, if so, how the instability evolve is yet to be fully investigated.rn rnIn this study, we use the Kippenhahn-Schlueter (K-S) prominence model as the base for 3-D numerical MHD simulations. The K-S prominence model is linearly stable for ideal MHD instabilities, but can be made unstable through nonlinear perturbations, which we impose through inserting a low density (high temperature) tube through the centre of the prominence. Our simulations follow the linear and nonlinear evolution of upflows propagationg from the hot tube through the K-S prominence model.rnrnWe excited Rayleigh-Taylor like modes inside the K-S model with a wave along the contact discontinuity created between the hot tube and the K-S prominence, and solved the perturbations of this system. The most unstable wavelength was $sim 100$ km which, through the inverse cascade process, created upflows of $sim 600$ km. The rising plumes obtained a constant rise velocity in the nonlinear stage due to the creation of adverse magnetic and gas pressure gradients at the top of the plume.
9
Anjali John K
Indian Institute of Astrophysics
poster
10
ANNALAKSHMI M.
MADURAI KAMARAJ UNIVERSITY
Studies on some properties of narrow CMEs during 23rd and 24th solar cycle minima
poster
In this report we investigated the properties (such as speed, angular width and location) of narrow CMEs (width ≤ 20º) and normal CMEs (>20º). In our present work, we have chosen the data from SOHO/LASCO during the periods of 1996-1997 and 2008-2009 corresponding to 23rd and 24th solar cycle minima. Interesting result from the analysis is that the CME width distributions of the two minima are very different, with a shift to much smaller widths in solar cycle 24. The detailed analysis and the results will be presented.
11
Arnab Rai Choudhuri
Indian Institute of Science
Back-reactions of dynamo-generated magnetic fields: torsional oscillations and variations in meridional circulation
oral
The solar dynamo produces magnetic fields which can react back on the flow patterns in the solar interior, causing a periodic variation with the solar cycle. A periodic variation of the angular velocity distribution known as torsional oscillations is known for some time. Of late, there seems to be increasing evidence that there is also a periodic variation of the meridional circulation with the solar cycle – the circulation becoming slightly weaker at the time of the sunspot maximum. Theoretical models involve calculating the Lorenz force of the dynamo-generated magnetic field and then solving the Navier-Stokes equations for the flows with this Lorenz force. I shall discuss the recent theoretical efforts in modeling the back-reactions of dynamo-generated magnetic fields.
12
Arun Mangalam
IIA
Generalized Force-Free configurations of magnetic fields
poster
We demonstrate new configurations of non-linear force free fields and explore its applications.
13
Ashok Ambastha
Physical Research Laboratory
Sub-surface flows in flaring and quiet active regions
oral
We have carried out a study on the statistical characteristic properties of subphotospheric flows of flare prolific and dormant active regions selected during August 2001-January 2007. We found that flare productive active regions possessed significantly stronger, twisted flows with depth as compared to the dormant regions. The flow characteristics show a new hemispheric rule and also indicate towards a possible relationship with life expectancy of ARs. We shall discuss these important recent results obtained from our extensive local helioseimic investigations.
14
Avijeet Prasad
IIA
Models of self-similar force-free spheres and its applications to solar active regions
poster
We have investigated linear and non-linear separable spherical models ofrnforce-free fields, in particular, the energy, relative helicity andrnother invariants. We apply this technique to build a full threerndimensional and three component model from observations of tworndimensional and three component vector magnetogram data obtained fromrnthe spectro-polarimeter on board HINODE satellite. We have characterized therndegree of correlation of observed fields with models. We will describernthe data reduction procedures followed and the technique that has beenrnapplied to 6 vector magnetograms, two of whichrninvolve the configurations observed before and after X class flarernevents. We report favourable comparisons of our models (correlations arernfound to be 70 -90%) to the relative helicity and free energy inferredrnfrom the flare observations. We describe improved models to be built inrnthe future that can be tested with more observations.
15
Awasthi Arun Kumar
Physical Research Laboratory
Multi-wavelength Diagnostics of the Precursor phase in Solar flares
oral
It is widely known that a few solar flares reveal precursor phase. However, the physical process of formation of precursors has not been understood so far due to lack of high spectral and temporal cadence observations. We study the flare plasma parameters in X-ray and EUV wavebands during precursor phase of 20 flares observed between 2003 and 2004. We employ soft X-ray observations made by the Si detector of Solar X-ray Spectrometer (SOXS) mission and EUV observations from TRACE mission. The Si detector provides spectra with high energy resolution of ~0.8 keV in the energy range of 4-25 keV with the cadence of 3 sec and 100ms during quiet and flare modes respectively. We employ the 2-5 min integrated spectra in 4-10 keV in precursor phase in order to estimate temperature (T), emission measure (EM) and relative abundance (A) of Fe and Ni line features with the help of SolarSoft package. We found flare plasma during precursor phase to be of isothermal nature. This suggests conductive-driven heating. However, in some flares we found both conductive as well as beam-driven heating. The T, EM and A are found to vary between 7-20 MK, 0.01-0.08 X 10^49 cm^-3 and 0.1-0.5 respectively. The spatial characteristics of this low temperature flare plasma are further studied employing 171 and 195 Å images from TRACE mission and Hα observations. We found that the precursor phase emission is originated from low altitude chromospheric loops. This study, in context to the RHESSI images will further enable us to explore the spatial relation between precursor and main phase energy release site.
16
B. Ravindra
Indian Institute of Astrophysics
On the Evolution of Spinning and Braiding Helicities in AR 10930
oral
Magnetic helicity is an important tool to understand the twist, kink and deformation of the magnetic fluxtubes in the solar atmosphere. The magnetic helicity is also believed to be playing a key role in solar flares and coronal mass ejections. Longcope et al. (2007) decomposed the magnetic helicity fluxes into spinning and braiding terms. Active region NOAA 10930 is a flarernproductive region and it is well observed by Hinode satellite at various wavelengths. In this rntalk, I will present the evolution of spinning and braiding helicities in AR 10930 determined rnusing the high-resolution magnetograms. A comparison of the magnitude and sign of spinning and braiding helicities over a period of 5 days leading up to the X-class flare will be presented.
17
B. S. Nagabhushana
Indian Institute of Astrophysics:
MODEL FOR SOLAR GRANULES
poster
A model for solar granules is developed by considering the plane parallel geometry. The above equations are solvedrnsimultaneously for one dimensional in Cartesian co-ordinaternsystem. We assumernthat the energy loss is mainly due to radiative losses.rnThe variations of physical variables are taken only along therndirection where the gravity acts. The purpose of this modelrnis to explain the sensitivity of radiative losses with the properties of the fluid (like temperature, pressure, density and velocity of the fluid).rnrnrn
18
Badruddin
Aligarh Muslim University
SOLAR WIND PLASMA/FIELD PROPERTIES OF INTERPLANETARY CORONAL MASS EJECTIONS OF DIFFERENET GEOEFFECTIVENESS
poster
We study the solar wind plasma and field properties of interplanetary coronal mass ejections (ICMEs) responsible for weak ( -30 nT
19
Bagare, S. P.
IIA, Bangalore
Site characterization for the proposed National Large Solar Telescope in India
poster
The Indian Institute of Astrophysics has initiated efforts towards building a modern major solar observational facility in the country, the National Large Solar Telescope (NLST). Preliminary studies to locate prospective sites started in mid-2006. Two sites in the high mountain desert of Ladakh, Hanle & Merak, and one sub-Himalayan site Devasthal, were selected for detailed characterization. Hanle and Devasthal are the observatory sites of IIA and ARIES respectively. The new site Merak is located on the shore of the Pangong lake. rnrnAn array of instruments such as Solar Differential Image Motion Monitor, a Shadow Band Ranger, High cadence Automatic Weather Station, All-sky Camera, Micro Thermal device on 15 m tower, Pyrheliometer and Sky Radiometer were used at the stations. Sufficient data has been obtained to characterize both Hanle and Merak. Observations at Devasthal site is under progress and preliminary inferences can be made. We present the highlights of the results obtained so far for each of these sites. rnrnIt emerges that the high altitude lake site, Merak, has excellent conditions which are required for a two meter class solar telescope having adaptive optics for maximizing the benefits of the excellent day time conditions. Hanle appears to be the next choice with significant periods of good conditions, particularly in the forenoon period. The data from Devasthal site are under study for detailed evaluation.
20
Cheng Fang
Nanjing University
History and Progress of Solar Research in China
invited
After briefly mentioning Chinese ancient records of the Sun, we describe the beginnings of modern solar research in China in the 20th century. The main contents are focused on the progress of solar research in China after 1950’s, including the developments of solar research in Purple Mountain Observatory, Yunnan Observatory, Beijing Observatory and some astronomy departments in universities. In particular, the constructions of solar observational facilities, the increase of solar researchers and students, as well as the topics of solar research since 1980’s have been described in detail. Some problems are also discussed.
21
Chia-Hsien Lin
Graduate Institute of Space Science, National Central University
Investigating the initiation mechanisms of coronal mass ejections
invited
Coronal mass ejections (CMEs) are the ejections of large amount of plasma and magnetic flux from the solar surface.rnThe ejections can travel through the entire interplanetary space,rnand affect our space activities and instruments.rnAlthough such spectacular events have been studied for decades, how they are initiated is still under debate, mainly due to the difficulties in both observations and theoretical computations.rnrnThe objective of this study is to investigate the possible initiation mechanisms of such events by comparing, both qualitatively and quantitatively,rnthe observed properties and temporal variations withrnthe predictions from theoretical models.rnrnIn this talk, I will first briefly describe the CME models selected for this study, then explain our investigation strategy,rnand lastly present our current results.rn
22
Dean-Yi Chou
National Tsing Hua University, Taiwan
Probing Magnetic Fields in the Solar Convection Zone with Helioseismology
invited
Helioseismology uses solar p-mode waves to probe the structure of thernsolar interior. The modifications of wave properties due to the presencernof solar magnetic fields provide information on the magnetic fields in rnthe solar interior. This modification decreases rapidly with depth rnbecause of the rapid increase in plasma pressure. This fact makes rnthe detection of the magnetic fields in the deep convection zone rndifficult. Here we review different methods, including ring diagram, time-distance, and acoustic imaging (seismic holography), and their important results.
23
DENG Yuanyong
National Astronomical Observatories
Introduction to Chinese Giant Solar Telescope
oral
Chinese solar community has proposed a next generation ground-based solar telescope---Chinese Giant Solar Telescope (CGST). CGST will be an Infrared and Optical telescope, with spatial resolution equivalent to 8m and light-gathering power equivalent to 5m. A brief introduction to CGST will be given in this presentation.
24
Dibyendu Nandy
IISER Kolkata
Dynamo Models of the Solar Cycle: Current Trends and Future Prospects
invited
The magnetic cycle of the Sun, as manifested in the cyclic appearance of sunspots, significantly influences our space environment and space-based technologies by generating what is now termed as space weather. Long-term variation in the Sun’s magnetic output also influences our climate through modulation of the total solar irradiance. In this talk I will review the current state of understanding of this magnetic cycle and comment on outstanding issues that is likely to drive future research in this field.
25
Dipankar Banerjee
Indian Institute of Astrophysics
Waves in the Corona
invited
With modern imaging and spectral instruments the detection ofrnoscillations in the solar corona has become a routinernevent. These oscillations are considered to be the signatures of arnwave phenomenon and are generally interpreted in terms ofrnmagnetohydrodynamic (MHD) waves. With multi-wavelength observationsrnfrom ground and space-based instruments, it has been possible torndetect waves in a number of different wavelengths simultaneously and,rnconsequently, to study their propagation properties. Observed MHDrnwaves propagating from the lower solar atmosphere into the higherrnregions of the magnetized corona have the potential to provide anrnexcellent insight into the physical processes at work at therncoupling point between these different regions of the Sun. In this talk I will review the current status of observations of waves in the corona. I will also point out the difficulty in the interpretation of waves through imaging observations alone. In this context the recent debate on waves versus flows will be reviewed. rn
26
Donguk Song
Seoul National University
Structures of A Solar Filament Observed with FISS on 2010 July 29 ; Spine and Barb
oral
In general, solar filaments are divided into two parts; one spine and several barbs. Barbs are seen as if they protrudes from the spine. Until now there are many controversies about the structures of a barb and spine. Recently, New Solar Telescope was installed at Big Bear Solar Observatory. Its clear aperture is about 1.6m and it is the largest telescope among ground-based solar telescopes. Fast Imaging Solar Spectrograph (FISS) developed by SNU and KASI was also installed in a vertical optical table in Coude room of the 1.6m NST.It is simultaneously able to record two lines; Ha and Ca II 8542A line. On 2010 July 29, we observed a portion of a solar filament located in northern hemisphere using FISS and it had a well-developed barb. And we also observed a potion of a spine. In order to analyze the data, we used the cloud model and obtained physical quantities of the solar filament.Temperature of the solar lament ranged between 4500 to 12000K and non-thermal velocity ranged between 3 to 6.5km/s. By comparing physical quantities of a barb and spine, we try to understand these structures of the solar filament.
27
Dr Ajaysinh K Jadeja
Gujarat Ayurved University
Studies of CMEs Using Ooty and Rajkot Radio Telescopes
poster
Coronal mass ejections are an important factor in coronal and interplanetary dynamics. They inject large amounts of mass and magnetic fields into the heliosphere, causing major geomagnetic storms and interplanetary shocks. In this paper large angle CMEs (angular width>120 degree) has been studied using Ooty and Rajkot Radio Telescopes. These IPS telescopes operated at 327 MHz and 103 MHz respectively and they are used extensively to track and study interplanetary disturbances. Various geoeffective CMEs occurred between the years 2000-2003 are described in this paper along with their space weather effects. An m-p curve for few radio sources observed by Ooty and Rajkot also presented.rn Keywords: IPS- Interplanetary Scintillation; IPM- Interplanetary Medium; CME- Coronal Mass Ejection.rn
28
Dr. Abhishek Kumar Srivastava
ARIES, Nainital
Transient Induced MHD Oscillations : A Tool to Probe the Solar Active Regions
oral
Solar transients and eruptive phenomena are ubiquitous in the solar plasma, and are central issues recent days in the field of solar physics. The observations of the emissions over entire electromagnetic spectrum in such highly dynamical processes of large and small-scale transient/eruptive events, highly dynamic magnetic field configuration, energetic particles provide the clues of plasma processes at mega-Kelvin temperature coupled with very complex magnetic field as well as energy build-up/energy-release processes involved in such events. The most phenomenological aspect related to the solar eruptive phenomena is the induced magnetohydrodynamic (MHD) oscillations generated during these energetic processes, which are being useful to diagnose the solar active regions. In this paper, we review the recent trends of the transient (e.g., flare and CME) induced quasi periodic oscillations in solar atmosphere and discuss their implications and potentials to diagnose the solar active regions, which provide the clue of local plasma dynamics and heating. We also discuss the future aspects of these phenomena under the light of upcoming multi-wavelength observations and theoretical developments, which will have significant roles to understand the new aspects of solar atmosphere in the upcoming solar cycle 24 and its anticipated intense maximum in 2012.
29
Dr. Partha Chowdhury
Department of Physics, University of Calcutta
A study of the North–South Asymmetry of sunspot areas during cycle 23
oral
Solar activity indices vary over the Sun’s disk, and various activity parameters are not considered to be symmetric between the northern and southern hemispheres of the Sun. The north-south asymmetries of different solar indices provide important clues to understanding solar dynamo action, especially with the modern non-linear dynamo models. In the present work, we study the statistical significance of north–south asymmetry of sunspot areas for the complete solar cycle 23 (1996 – 2008). The dominant hemisphere in each year of the cycle 23 has been identified by calculating the probability of hemispheric distribution of sunspot areas. The statistically significant intermediate-term periodicities of the north-south asymmetry of sunspot area data have also been investigated by using wavelet technique. A number of short and mid-term periods are detected and most of them are found time variable. We will present our results and discuss possible explanations for different solar mid-term periodicities.
30
Dwivedi, Bhola
BHU
31
Ebenezer
Indian Institute of Astrophysics
Estimation of the coronal magnetic field from the Solar decametric continuum burst
oral
The solar particle event of January 20, 2005 was the spectacular of the space age and largest since 1956 in terms of ~GeV protons at Earth. It is associated with fast Coronal mass ejection ranging from ~ 2500 - 3700 km/s and a very large x-ray flare (X7.1). This event was observed from Gauribidanur radio observatory in the frequency range from 30 -330 MHz. We compute the coronal magnetic field from the photospheric magnetograms using potential field extrapolation assuming ( j x B =0 & ∇.B=0) as the potential fields minimize the magnetic energy . These results are compared with radio observations pointed to absorption by ambient plasma at low frequencies using Razin-Tsytovitch effect.rn
32
Eijiro HIEI
National Astronomical Observatory
Beginnings of solar research in Japan
invited
Beginnings of solar research in Japan will be reported on the following items; solar neutrino[Super-Kamiokande],helioseismology [Undo-Osaki’s theoretical work on oscillatory motions(1975)], solar dynamo[Yoshimura’s research on global magnetic oscillations (1972~1978)],photosphere-chromosphere[solar group’s work],corona[Miyamoto’s research on ionization equilibrium of FeI~FeXXVI (1943), and Notsuki’s work on coronal green line(1949~)],sunspot[Shin Hirayama’s first scientific obs. (1888), and Unno’s radiative transfer theory under magnetic field(1956)], flare[Suemoto’s method of Stark-broadening of hydrogen Balmer lines (1962), and solar group’s works], total solar eclipse [first overseas eclipse observation near Bombay by Terao et al.(1898), and Grazing Incidence Method (1958,1966) ] , radio observations [H.Tanaka’s absolute measurement of solar radio micro-wave(1973), Uchida’s research on Moreton-wave(1968)] space-observations of Hinotori satellite [K.Tanaka’s contribution], Yohkoh[Uchida’s], Hinode[Kosugi’s], and balloon[T.Hirayama’s], observing telescope [Einstein Solar Tower Telescope (Zeiss) (1929) set up by Saotome and Fujita, 10cm coronagraph (1949) by Notsuki, 25cm coudé type coronagraph (1972) by Nagasawa and Moriyama, 65cm coudè-type solar telescope (1968) by Suemoto and Makita, 70cm Coelostat (1961) and Domeless Solar Telescope at Hida Obs, (1979) by Miyamoto and Hattori, Radio Heliograph (1992) at Nobeyama Solar Radio Obs. by Kai et al. (1992) ] Archive solar data for future collaborative research will also be covered.
33
G Vigeesh
Indian Institute of Astrophysics
3D simulations of wave coupling in magnetised solar atmosphere
poster
The MHD processes involved in the heating of the solar atmosphere is still not fully understood. Our recent two-dimensional numerical studies of wave propagation in small scale magnetic flux concentrations suggest that flux tubes provide minimal acoustic energy to the chromosphere in the magnetic network of the Sun. However, they are an efficient source of acoustic heating to the surrounding non-magnetic regions. But these studies are limited by the fact that they use simple idealistic mechanism of wave excitation, they are in 2D and hence do not give a realistic picture. Our latest research aims at a study of these processes using state-of-the-art 3D numerical simulations. The highly dynamic nature of the solar photosphere is a rich source of waves, which are believed to be one of the possible and likely candidates responsible for heating the upper solar atmosphere. We explore the detailed dynamics and energy transport by a wide range of MHD waves in a 3D solar atmosphere which will considerably help us in understanding their role in the heating of solar chromosphere and corona.
34
G.S.Suryanarayana
INDIAN INSTITUTE OF ASTROPHYSICS
Type II bursts: Relationship between the Kinetic energy and Second harmonic
poster
I will update later
35
G.Sindhuja
Indian Institute of Astrophysics
Temporal variations in the Solar chromosphere-Ca K line profiles
poster
The previous studies show that there is a lack of information on the variation of network flux with solar cycle phase and also the center of solar disc was found to show no variation with solar cycle phase(white and Livingston 1978). A study on solar variability model (Skumanich et al 1984) shows that there is an excess component during the solar maximum phase. rnSo the above mentioned studies, forms the basis for the development of new program(Jagdev singh 1989) at kodaikanal tower telescope in 1986 to monitor Ca K line profiles as a function of latitude and integrated over the visible 180º longitude. The observations have been taken from 1986 onwards.rnThus the huge database will be used to study the various parameters of the Ca K line and to study the variation of network flux as a function of solar latitude with solar cycle phase. rnActivity related with sunspots has been studied widely but variations in the polar regions have not been observed systematically. Our data permits to study the changes in polar regions systematically and its implications to the magnetic cycle of the Sun.rnSo the observations, methods, data analysis procedures, preliminary results will be displayed.
36
Girjesh Gupta
Indian Institute of Astrophysics
On the nature of propagating MHD waves in polar coronal hole
oral
Waves play an important role in the heating of the solar corona and in the acceleration of the fast solar wind from polar Coronal Holes (pCHs). Recently using EIS/Hinode and SUMER/SoHO, we have reported the presence of accelerating waves in polar region (Gupta et al. 2010, ApJ, 718, 11). These waves appeared to be originating from a bright location on-disk, presumably the footpoint of the coronal funnels. These waves were interpreted in terms of either propagating Alfven waves or fast magneto-acoustic waves. The new sets of observations are obtained from the EIS/Hinode 2'' slit and imaging data from AIA/SDO in various filters over plume and inter-plume regions as HOP175 programm. The combination of spectroscopic and imaging data will provide further details on mode identification and properties of these waves and will help in the energy calculations. In this presentation, preliminary results obtained from these observations in terms of different nature of propagating waves in plume and inter-plume regions and energy carried by these waves will be presented.
37
H. M. Antia
Tata Institute of Fundamental Research
Seismic study of rotation in the solar interior
invited
Helioseismic data during the last 15 years covering entire solar cycle 23 have been used to study the rotation rate and its variation during thernsolar cycle. The temporally varying component of the rotation rate shows the well known bands of faster and slower than average rotation,rnwhich migrate toward the equator at low latitude and toward the poles at high latitudes. With the data covering two minima in solar activity it is also possible to study the variation between the two solar cycles.rn
38
Haisheng Ji
Purple Mountain Observatory
An observational overview of solar flares
invited
In this talk, we present an overview of solar flares and associated phenomena, trying to summarize rnobservational data primarily from SoHO, TRACE, and RHESSI era.rnAn emphasis is taken to describe the new observational results from rnmultiple points of view. We try to report a correlation among them and make a comaprison to existingrntheories and models. We conclude with a brief discussion of our research interests and future important observations.
39
Hari Om Vats
Physical Research Laboratory
North-South Asymmetry in Coronal Rotation
oral
For the estimation of solar coronal rotation we have extensively used the flux modulation method on the following solar observations:rn(1)The disk integrated radio flux at 2.8 GHz for the period of six solar cycles. This provided long term variability. This showed that there are two components in the variability of solar rotation period thus estimated, namely, 22 year period (corresponding to Hale cycle) and an irregular component.(2) Simultaneous multi-frequency (11) radio emissions over 26 months. This showed that there is a differential rotation as a function of altitude in the solar corona. The disk integrated measurements give no information on the latitude variation.(3) Radio images at 17 GHz for the period 1999-2005 gives very interesting information about the differential rotation of the solar corona at the height of these emission. The differential profile is shallower than those for photosphere and chromospheres. (4) YOHKOH SXT images for the period 1992 - 2001 show an yearly variability of the solar rotation as a function of latitude. The average profile is even shallower than that obtained by radio images at 17 GHz. The space time plots of solar coronal rotation period obtained both by radio and X-ray images give clear evidence of North-South asymmetry. This asymmetry chnages its sign in odd and even solar cycles.
40
Heesu Yang
Seoul National University
A Bright Rim of Solar Filament Observed by using FISS
oral
Bright rims are one of the most unknown part of a filament nowadays. Many models tried to explain the environments, but there is no commonly acceptable model.rnWe observed a bright rim on June 25, 2010 using Fast Imaging Solar Spectrograph(FISS) installed in New Solar Telescope, Big Bear Solar observatory. FISS can obtain a couple of waveband data simultaneously with short time cadence and fine resolution(∼ 0.1”, expected) with Adaptive Optics. To explain phenomena of the observed bright rim, we adopt the cloud model. We find that the bright rim has higher mean intensity than the other quite region. The higher mean intensity of the region can be caused by thermal heating or by just the increase of the radiation field. By fitting a couple of data with the model, we determine source function and optical thickness of the region, width of the line, and line shift for each Hα and CaII 8542 line. From these, we can infer temperature and non-thermal velocity. In our study, temperature of the bright rim is found to be about 30000K which is higher than the filament and about 10km/s non-thermal velocity which is the same with the filament. We investigate the physical origin of the apparent high tempereture of the rim.
41
Hideyuki Hotta
University of Tokyo
Parity of solar global magnetic field determined by turbulent diffusivity in solar flux-transport dynamo
oral
We investigate the criterion for the solar dipole-field in a kinematicrnflux-transport dynamo model.rnThe sun has a dipole-like global magnetic field. This field is thoughtrnto be generated by the dynamo action of the solar internal plasma.rnThe flux-transport dynamo succeeds to reproduce some features ofrnsolar cycle, e.g. poleward the migration of the general magnetic field andrnthe butterfly diagram.rnThe parity, however, of the global magnetic field significantly depends onrnparameters in the flux-transport dynamo.rnIt is known that the coupling of the magnetic field between hemispheresrndue to turbulent diffusivity is an important factor for the solar parityrnissue, but the detailedrncriterion for the generation of the dipole field has not been investigated.rnOur conclusions are as follows.rn(1) The stronger diffusivity near the surface is more likely to causernthe magnetic field to be a dipole.rn(2) The thinner layer of the strong diffusivity near the surface is alsornmore apt to generate a dipolar magnetic field.rn(3) The faster meridional flow is more prone to cause the magnetic fieldrnto be a quadrupole, i.e., symmetric about the equator.rnrnThe result (1) is consistent with our previous work (Hotta & Yokoyama,rn2010a), which is on the effect of the surface diffusivity for rnthe observed weak polar field.rn
42
Hiroaki Isobe
Unit of Synergetic Studies for Space, Kyoto University
Theoretical and numerical modeling of solar flare and magnetic reconnection
invited
Observationally, solar flare is sudden increase of electromagnetic emission in the solar atmosphere. In 90s, there has been a lot of discussion about the relationship of flares, coronal mass ejections and prominence eruptions. It is now widely accepted that they are different manifestations of common physical processes that involve plasma ejection and rnmagnetic reconnection (e.g., Shibata 1996; Fobes 2000). However, there still are significant open questions in the theory of flares: energy storage (why flare statistics show power low?), initiation mechanism (can we forcast flares?), and elementary physical processes (magnetic reconnection and particle acceleration). In this talk I will review recent progresses the theoretical and numerical modeling of solar flares. In particular I will focus on magnetic reconnection.
43
Hongqi Zhang
National Astronomical Observatories of China
Helicities of Solar Active Regions
invited
In this talk, the basic configuration of magnetic field and its evolution in the solar atmosphere have been discussed. The helicity is important to present the basic topological configuration of magnetic field transferred form the solar subatmosphere into the interplanetary space. The statistical distribution of magnetic field (and helicity) in solar atmosphere and its reversals are presented by means of the observational (vector) magnetograms. As the magnetic fields in the solar surface provides the information on the formation of magnetic field in the subatmosphere, the statistical analysis of the observational magnetic helicity is also important for the confirmation of the solar dynamo models.
44
Hui LI
Purple Mountain Observatory
Magnetic field configurations leading to solar eruptions
oral
Magnetic fields play an important role in eruptive phenomena on the Sun. In this presentation, I will talk about magnetic configurations that lead to eruptions on the Sun. Observations show that magnetic shear, magnetic null point, magnetic connectivity and magnetic topology are all important for the occurrence of solar eruptions. Based on our previous works, I will discuss the evolution and change of magnetic shear before and after an eruption take place, the roll the magnetic null point in the occurrence of solar flares, the variations of magnetic connectivity and topology in the episode of a solar eruption.
45
Hyungmin Park
Chungnam National University
Determination of physical parameters of prominences using FISS
oral
Prominences are one of the most prominent features in the chromosphere. Using Fast Imaging Solar Spectrograph (FISS) installed to the New Solar Telescope (NST) at Big Bear Solar Observatory, we observed two prominences at the east limb and the west limb on June 30, 2010. By applying a non-linear least square fitting of a radiative transfer model to the profiles of Ha line and CaII8542 line, we derived physical parameters of the prominences. The ranges of temperature and non-thermal velocity are determined to be 7500-13000K and 5-11km/s, respectively. The maximum temperature of prominences is found to be below 20,000K. We also found the tendency that temperature increases with height.
46
Jagdev Singh
Indian Institute of Astrophysics
Coronal Heating: Visible emission line space coronagraph
invited
The Kodaikanal observatory, the field station of Indian Institute ofrnAstrophysics has been making synoptic observations of the sun since 1904rnby taking the images of the sun in continuum, Ca-K line and H-alpha line.rnWe have augmented the facilities by fabricating and installing the TWINrntelescope that enables us to take continuum and Ca-K line images of thernsun at the cadence of about 30 seconds using 2K x 2K CCD cameras withrnpixel size of 13.5 x 13.5 microns. We are in the process installing arnH-alpha telescope with 20cm aperture telescope to take images of the sunrnwith a similar cadence. In addition we have digitized the images of thernsun in Ca-K line available at the observatory since 1907 and developingrnthe soft ware to estimate Ca-K parameters. The raw images of these datarnwill be available at the IIA website in near future. Now we have startedrndigitizing the continuum images of the sun. The Solar Tower Telescope withrnhigh spatial and spectral resolution is being used to study the Ca-K linernprofiles of the sun as a function of latitude and integrated over thernvisible solar disc on daily basis to study the temporal variations in thernchromosphere with the phase of solar cycle.rnWe have also been planning the expeditions to make observations of thernsolar corona during total solar eclipses to understand heating of thernsolar corona. Here we discuss the systematic temporal variations observedrnin the green and red emission profiles using high spectral and temporalrnobservations during the 2006, 2009 and 2010 total solar eclipses.
47
Jagdev Singh
Indian Institute of Astrophysics
Twin Telescope in Kodaikanal Solar Observatory: The Temporal Variations of the Network Index During the Declining Phase of Solar Cycle 23
poster
We have installed new a telescope named as TWIN TELESCOPE at Kodaikanal observatory to continue the synoptic observation of the sun those are being obtained since 1904. This telescope using 15-cm objectives is capable of taking Ca-K line filtergrams and photoheliograms in continuum of the full-disk of the sun. The telescope is in operation since 2008 and images are being obtained at the cadence of 5 minutes. We have developed a novel technique to determine the plage index and the network index. The result shows that rnthe percentage of the network index varies marginally with the seeing conditions during the day. The application of the technique on the calibrated Ca II K images shows that the network elements occupy about 30% of the sun’s visible disk. During the solar minimum period of observations the network index is observed to vary a little over the time.
48
Javaraiah Javaraiah
Indian Institute of Astrophysics, Bangalore-560034
DOES THE SUN\'S SURFACE EQUATORIAL ROTATION RATE VARY ?
oral
We have analysed the Solar Optical Observatory sunspot group data and the Mt. Wilson Doppler-velocity measurements during the period 1986-2007 and determined the variations in the annual mean values of the equatorial rotation rates (the intercept term, `A', in the equations of the traditional laws of the solar differential rotation) of the sunspot groups and the Sun's surface. We find that the solar cycle variation in `A' determined from the Mt. Wilsonrn Doppler velocity data substantially differs with the corresponding variationrnin `A' determined from the sunspot group data that did not include the values of the abnormal angular motions of the spot groups, whereas closely resembles to the corresponding variation in `A' determined from the spot group data that included the values of the abnormal angular motions. A reason for this could be the solar rotation rates determined from the spot group data with and without the contributions of the abnormal angular motions of the spot groups may represent the rotation rates of the sallower layers and the relatively deeper layers of the Sun, respectively. These results may confirm the existence of the solar cycle variation in the surface `A' determined from the Doppler-velocity measurements, which is doubted so far as an artifact of inconsistency in the data due to the frequent changes in the Mt. Wilson spectrograph instrumentation.
49
JAYAPAL R
MAHATMA GANDHI UNIVERSITY, P D HILLS P O, KOTTAYAM-686560,KERALA,INDIA
STABILITY OF ELECTROMAGNETIC WAVES IN THE SOLAR WIND DRIVEN BY NEGATIVELY CHARGED OXYGEN OF COMETARY ORIGIN
poster
The ionization of neutral atoms and molecules as they stream away from a comet corresponds to the introduction of a free energy source in to the solar wind. Positively ionized oxygen ions (O+) has been observed in the plasma environments of a number of comets; in addition, negatively charged oxygen ions ( O- ) has also been observed in the plasma environment of comet Halley. Thus both O+ and O- ions can be picked up by the solar wind.rn If there is a non zero angle between the solar wind flow velocity, Vsw,, and the average interplanetary magnetic field, B0, then the introduction of cometary ions initially leads to a ring-beam distribution that can excite a number of instabilities.rn We, therefore, study the stability of both right- and left-circularly polarised electromagnetic waves in a multi-ion plasma: the solar wind contributing hydrogen ions and electrons; the cometary environment contributing hydrogen, O+, O- and electrons to the plasma composition.rn We find that the propagation characteristics of the left circularly polarized wave to be independent of O- densities below the hydrogen ion gyro-frequency. The growth rate of this mode which increases with increasing drift velocities does not show a consistent behavior with regard to O- densities.rn For the right circularly polarized wave, the propagation characteristics below the hydrogen ion gyro- frequency is, however, a function of the O- densities. The growth rate which increases with increasing drift velocities again does not vary consistently with regard to O- densities.rn
50
Jie Jiang
National Astronomical Observatories, Chinese Academy of Sciences
A physical reconstruction of solar magnetic field since 1700
on
We have used semi-synthetic records of emerging sunspot groups based on sunspot number data as input for a surface flux transport model to reconstruct the evolution of the large-scale solar magnetic field and the open heliospheric flux from the year 1700 onward. The statistical properties of the semi-synthetic sunspot group records reflect those of the observed the Royal Greenwich Observatory photoheliographic results. These include correlations between the sunspot numbers and sunspot group latitudes, longitudes, areas and tilt angles. The reconstruction results for the total surface flux, the polar field, and the heliospheric open flux (determined by a current sheet source surface extrapolation) agree well with the available observational or empirically derived data and reconstructions. We confirm a significant positive correlation between the polar field during activity minimum periods and the strength of the subsequent sunspot cycle, which has implications for flux transport dynamo models for the solar cycle. Just prior to the Dalton minimum, at the end of the 18th century, a long cycle was followed by a weak cycle. We find that introducing a possibly `lost' cycle between 1793 and 1800 leads to a shift of the minimum of the open flux by 15 years which is inconsistent with the cosmogenic isotope record.
51
Jingxiu Wang
National Astronomical Obs., Chinese Academy of Sci.
Solar Cycle in term of Small-Scale Magnetic Elements
oral
No any other astrophysical process but solar cycle leaves massive footprints on human’s living environment. This eleven-year cycle has been illustrated by sunspot number changes since 1840s, and is considered as the manifestation of a mean-field magnetohydrodynamic dynamo operating deeply in the solar convection zone. However, observations have revealedrnthe ubiquitous small-scale magnetic elements which bring much more magnetic flux thanrnsunspots do. Are they associated with sunspots and behaving as part of solar cycle? With the unique database from the Michelson Doppler Imager onboard the Solar and HeliosphericrnObservatory in an interval embodying Solar Cycle 23, here we show that small-scale magnetic elements dominate the Sun’s magnetic flux over 60% of the duration of the cycle; with decreasing flux per element, their number and total flux follow in-phase, anti-phase and nophasernchanges with sunspots. The anti-phased component cupies more than 80% of total elements and more than 40% of quiet Sun flux. This revelation seems to resolve the long-standing puzzle of the anti-phase variation of solar small-scale magnetic activity.
52
Jongchul Chae
Seoul National University
The Sun Observed with the Fast Imaging Solar Spectrograph on the 1.6 meter New Solar Telescope at Big Bear
invited
In order to carry out spectral observations of the Sun with high spectral resolution and wide spectral coverage as well as high spatial resolution and high temporal resolution, we developed an Echelle spectrograph named Fast Imaging Solar Spectrograph (FISS), and installed it in a vertical optical table in the Coude room of the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. With the aid of the adaptive optics, the instrument does imaging of high quality, based on the fast scan of the slit across the field of view. Even though the instrument can cover any part of the visible and near infrared spectrum, it usually records the H alpha band and the CaII 8542 A band simultaneously using two CCD cameras, providing data quite suited for the study of structure and dynamics of the chromosphere and filaments/prominences. We describe how to process data and present some images and spectra taken from the early runs.
53
Jun Lin
Yunnan Astronomical Observatory
Evidence of Turbulence Reconnection In CME/Flare Current Sheets: Observations and Theories
oral
One of the most significant predictions of the catastrophe model of solar eruptions developed by Lin & Forbes (2000) is a long current sheet that forms following the onset of the eruption. Various modes of plasma turbulence as a result of plasma instabilities are invoked inside the current sheet, yielding fast dissipation of the magnetic field, namely magnetic reconnection, through the sheet. Because the timescale of reconnection is long compared to the timescale of the onset stage, dissipation of the sheet is slow, so the current sheet is able to become fairly long. The evolution in the global feature of the current sheet is significant constrained by the local Alfven speed, and the internal properties and features of the sheet, on the other hand, are dependent in an apparent way on the development of the turbulence caused by the instabilities. The tearing mode instability among those that may occur in the sheet is the most important one that accounts for the large thickness and high electric resistivity of the current sheet. In the present work, we show a set of events that were observed to develop long and thick current sheets with several apparent features indicating the progress of the turbulence in the sheet, and the results of numerical experiments of magnetic reconnection occurring in a long current sheet. We noticed that apparent features of the tearing usually appear in the environment of high magnetic Reynolds number, and numerical experiment duplicated the scaling of the current sheet deduced on the basis of the tearing mode.
54
K. Chandrashekhar
Indian Institute of Astrophysics
Study of a X-ray Jet and Bright Point Characteristics in Polar Coronal Hole Region
oral
High spatial and temporal resolution of the quite Sun transition rnregion and coronal hole region show a dynamical environment where brightrn points, mass flows and jets are commonly observed. We present a study of rna polar jet and bright points observed on 15 th April 2007 with a combination rnof imaging and spectral instruments on board SoHO and Hinode. We measure thernjet parameters length, width, life time, outward speed. The evolution of jet and rncorresponding bright point is observed in X-ray images taken by XRT/Hinode.rn Part of the Jet is also observed using EIS/Hinode slot images. rnCDS/SoHO points to the region near the foot point of the jet. Jet speed is measured rnusing stack plot method (time -distance map). Jet speed is measured using different rnmethods gives average value of 160 km s^{-1}. rnWe have identified five X-ray Bright Points ( XBP's ) for analyzing the variation rnof intensity from XRT images. We applied wavelet analysis to study the oscillations rnof these XBP's. All the five XBP's identified show intensity oscillations with periodsrnin between 20 to 40 minutes in their light curves with multiple peaks. The observation suggest magnetic rnreconnection between emerging flux and ambient open field in rnthe polar coronal hole.
55
K. M. Hiremath
Indian Institute of Astrophysics
Dynamic and Magnetic Evolution of Sunspots from the Hinode Data
poster
HINODE SOT/SP images are used for the measurements of evolutionary strengths of magnetic and dynamic structures (with their angle of inclination) of umbra, penumbra and the whole sunspot.rnDetails of these results, especially comparison of observed evolutionrnof average Evershed flow velocity field structure of sunspots with thernmodeled (Gokhale and Hiremath, 1986, Advance Space Res, 6, 47) Evershed flow velocity field structure are compared.rn Although measured spatial Evershed flow structurernis same as the measured spatial structure in the previous studies, signs of the velocity flow in eastern and western parts of penumbra reverse during the sunspot's life span. It is found that on average umbra and penumbra regions experience nearly equal and opposite dynamic forces during the life span of a spot as predicted by Gokhale and Hiremath's Evershed flow model.
56
K. Mahalakshmi
Radio Astronomy Centre, Ooty
Two successive mass ejections from AR0715 on 30 December 2004 and their near-sun signatures
poster
The initiation of an eruption on 30 December 2004 at 10:57 UT with an initial speed ~1250 km/s has been studied using multiwavelength data. This eruption shows two successive mass ejections, which are covered in EIT images at 10:27 UT and 10:51 UT from the same acive region AR0715. The filament activation starts at 10:15 UT which is associated with a C class flare in the location N03E53 at 10:10 UT, followed by the first eruption during 10:27 – 10:37 UT. EIT waves originating at the eruption site propagated to the whole of the disk. The shock (Type II burst in the frequency range 40 – 80 MHz) from 10:42 UT to 10:44 UT propagates with the speed of 1290 km/s in the coronal region. The second eruption occurred in the south west of first eruption site is likely linked to the large scale magnetic activity between these sites. The presence of type I burst (10:50 – 11:30 UT) provides support that the small scale reconnections have occurred on the activity site and nearby regions. The distortion of loop systems also are seen in EIT images, when the waves propagate. The drifting radio feature is seen in the spectrum (10:49 – 10:53 UT) in the frequency range 50 – 70 MHz. A brightening is observed at 10:49 UT in the EUV emission. It is likely to be linked to the expanding arch system and opening of field lines (Type III at 10:53 UT provides the evidence for opening of field lines). This study provides evidence for associated EUV and radio signatures of CME eruption.
57
K. Sankarasubramanian
ISRO Satellite Centre
SoLEXS: A low-energy X-ray Spectrometer for Solar Coronal Studies
oral
Solar Low-energy X-ray Spectrometer (SoLEXS), a high spectral resolution (≤ 250 eV at 5.9 keV) with soft X-ray energy coverage (down to 1 keV), is being proposed as an additional payload on-board Aditya-1. The motivation is to complement and support the space solar coronagraph, the main payload of Aditya-1. The science goals in which SoLEXS data will help with the main payload are: (i) Provide complimentary data during flares (micro- to regular flares) in order to study the DC heating mechanism while the main payload studies the AC heating mechanism. (ii) Flare observations from this payload along with the CME observations from the main payload will help in the study of Flare-CME association. This would then be the first mission providing both data from the same platform and hence accurate temporal relation can be arrived at. (iii) High spectral resolution combined with low energy threshold will provide independent accurate estimates of temperature and emission measure at the flaring sites which can then be compared with that obtained from the visible emission lines. Apart from these major science goals, this instrument can also provide a flare trigger to the main payload for CME observations since all CMEs have associated flares. In doing so, provide a means of optimizing the on-board memory storage during the CME mode observation of the main payload. In this paper, the details of the main science goals of the SoLEXS and its complementary nature to the main payload will be discussed. The instrument design as well as preliminary laboratory testing will also be highlighted.
58
K.E.Rangarajan
IIA
Small Sclae Chromospheric Velocity Structures
oral
I am a co-author with Nagaraju, so please refer to the abstract as submitted by Nagaraju
59
K.R.Subramanian
Indian Institute of Astrophysics
Statistical study of limb DH type II bursts and their association with CMEs and flares
poster
We have made a statistical analysis of the characteristics of 34 limb DH type II bursts observed during the period January 1997 to December 2005 in the frequency range of 14 to 1 MHz and their association with coronal mass ejections and flares. Limb events have no projection effects and therefore the speed measurements are more accurate. About 71 % of the bursts have start frequency of 14 MHz and about 94 % of the bursts have end frequency in the range of 1 to 6 MHz. The average life time of these limb DH type II bursts is ~ 125 minutes. It is found that the magnitude of the drift rates of these limb DH type II bursts are correlated with their starting frequencies. Saito's density model with a density enhancement factor of 10 is used to derive the heights corresponding to the start and end frequencies. From these heights for the DH type II bursts and their corresponding life times, the shock speeds of DH type II bursts are estimated. Significant correlation is found between the speeds of DH type II bursts and the speeds of CMEs. The formation heights of most of these DH type II bursts were found to be close to the leading edge of the CMEs for the density model we have used. The flares associated with limb DH type II bursts can be classified into mainly 3 types C, M and X.rnrn
60
KyungSuk Cho
Korea Astronomy & Space Science Institute
High Resolution Observation of Tiny Pores
invited
We investigate the temporal variation of several tiny pores smaller than 2 arcsec. These pores were observed by the Solar Optical Telescope (SOT) onboard Hinode on 2006 December 29. We have analyzed the high resolution spectropolarimetric (SP) data and the G-band filtergrams taken during the observation. Magnetic flux density and Doppler velocities of the pores are estimated by applying the center of gravity (COG) method to the SP data. The horizontal motions in and around the pores are tracked by adopting the Nonlinear Affine Velocity Estimator (NAVE) method to the G-band filter images. As results, we found the followings. (1) Darkness of pores is positively correlated with magnetic flux density. (2) Downflows always exist inside and around the pores. (3) The speed of downflows inside the pores is negatively correlated with their darkness. (4) The pores are surrounded by strong downflows. (5) Brightness changes of the pores are correlated with the divergence of mass flow (correlation coefficient $>$ 0.9). (6) The pores in the growing phase are associated with the converging flow pattern and the pores in the decay phase with the diverging flow pattern. Our results support the idea that a pore grows as magnetic flux density increases due to the convergence of ambient mass flow and it decays with the decrease of the flux density due to the diverging mass flow. In this talk, we also present preliminary results of coordinate observation between Hinode and New Solar Telescope.
61
Lakshmi Pradeep Chitta
Indian Institute of Astrophysics
Interaction of acoustic waves and intensity oscillations with small scale magnetic features
oral
Observations of solar line of sight velocity and intensity show a strong coupling with the magnetic field. From earlier observations, it is evident that extended structures of magnetic field (active regions like sun-spot and plages) interact with the acoustic waves and intensity oscillations in many ways. Scattering of acoustic waves and absorption of acoustic power over a spectrum of frequencies at active regions are well studied phenomena. In this work, we discuss the results of the interaction of magnetic field with the velocity field & G-band intensity at much smaller spatial scales . We also present the first results of center-to-limb variation of acoustic power in and surrounding small scale magnetic fields in quiet sun.
62
Leonid Kitchatinov
Institute for Solar-Terrestrial Physics
Solar differential rotation: origin, models and implications for dynamo
invited
Current status of the theory of differential rotation in stellar convection zones is reviewed. The leading theoretical concept explains the differential rotation as a result of interaction between solar convection and rotation. The concept agrees well with heliosesmology that shows inhomogeneous rotation in convection zone and its closest vicinity only. The numerical model based on the theory reproduces the solar rotation in excellent agreement with observations. The model computes the meridional flow also and predicts that the flow at the bottom of CZ is not small compared to the surface. The meridional flow near the bottom where turbulent diffusivity is small can be important for dynamo. Rigid rotation in the bulk of radiation core and the slender tachocline on its top can both be explained by an effect of an internal magnetic field of relic origin. Predictions for stellar differential rotation as function of the stellar mass and rotation rate are briefly discussed and confronted with observations.
63
Liyun Zhang
National Astronomical Observatories, Chinese Academy of Sciences
Long-term variation of solar surface differential rotation
poster
Recently, the surface differential rotation parameters were found to vary differently with time for the northern and southern hemispheres of the Sun. Both sunspots and flares strongly suggest that the northern hemisphere rotated considerably faster than the southern hemisphere during the last three solar cycles, which suggests a strong north-south asymmetry in solar surface rotation. In order to study the long-term variation pattern or period of solar surface differential rotation for each hemisphere, the location of sunspots during 1877-2009 in northern and southern hemispheres is analyzed, respectively. The variation of the rotation of the northern hemisphere is found to have an anti-correlation with that of the southern hemisphere during the last 12 solar cycles and the variation suggests a period of about 11-12 cycles.
64
Lovely, M. R
Indian Institute of Astrophysics
Tilt Angle of the Bipolar Sunspots During Their Initial Appearance
poster
Evolutionary physical properties of the sunspots on the surfacernare supposed to be indicators of subsurfacerndynamics, thermal and magnetic field structures of thernsolar convective envelope. For example, from thernanalysis of more than hundred years of sunspot data from the GreenwichrnPhotoheliographic Results, Hiremath (Astronomy & Astrophysics, 386, 674, 2002rn and references there in) concluded that, for differentrnlife spans (that anchor at different depths), variation of rotationrnrates of the sunspot groups during their initialrnappearance on the surface is almost similar to the radial variationrnof angular velocity of the convective envelope. UsingrnSOHO/MDI magnetograms and continuum images, it isrnpossible to estimate strengths of magnetic structurernof the sunspots (Hiremath and LovelyrnApJ, 667, 58, 2007; Lovely, M. R. Ph.D thesis, 2010) atrndifferent anchoring depths and to infer preliminaryrninformation on the thermal stratification (Hiremath and Akshatha 2010) of thernconvective envelope.rn In the present study, by using three years of SOHO/MDI magnetograms,rntilt angle, magnetic fluxes of the leader and the followerrnand their separation distance of the bipolar sunspots during their initialrnappearance on the surface are measured. Irrespectivernof their latitude and area, preliminary resultsrnshow that, tilt angle of the bipolar spots varies with different life spansrn giving a clue to radial variation of angular velocity and strengthrnof magnetic field structure of the convective envelope.rn
65
M. S. Wheatland
The University of Sydney
Modelling magnetic fields in the corona using nonlinear force-free fields
invited
Force-free magnetic fields, for which the magnetic or Lorentz force is self-balancing and hence zero, provide a simple model for fields in the Sun's corona. In principle the model may be solved using boundary values of the field derived from observations, e.g. data from the Hinode Spectro-polarimeter. In practise the boundary data is found to be inconsistent with the model, most likely because fields at the photospheric level are subject to non-magnetic forces. The "self-consistency" procedure (Wheatland & Regnier 2009) provides an approach to resolving the problem. This talk reports on results achieved with the procedure, in particular new results obtained for active region AR 10953 using Hinode data incorporating uncertainties in the boundary field values (Wheatland & Leka 2010).
66
Manjunath Hegde
Indian Institute of Astrophysics
Coronal Hole Oscillations Inferred from SDO/AIA Data
poster
In recent years, after well known sunspots,rnevidences are building up that occurrencernof solar coronal holes influence thernearth's atmosphere and climate. As partrnof ISRO funded project, we plan tornstudy the thermal and dynamic propertiesrnof the coronal holes. In the presentrnstudy, with high temporal resolution (12 sec) of about one hourrnduration, data of coronal hole structure in 193 Arntaken from SDO/AIA images are considered forrnexamination of oscillations. Average DN countsrnof whole coronal hole structure is computedrnand subjected to FFT. Preliminary resultsrnindicate the periodicity of 400 and 100 secs.rnThe 400 sec periodicity is dominant andrnpower is significant above three sigma level, wherernas less dominant 100 sec periodicity has power barely significantrnabove one sigma level. Based on the magneticrnand density field structures, it isrnsurmised that nature of these oscillations arerndue to Alfven wave disturbances that are supposed to bernoriginated from the deep interior and travelrnupto corona. In order to confirm whetherrnthese waves are standing oscillations or propagatingrnwaves, we also would like to analyze more numberrnof data set of coronal hole structures in differentrnwavelengths as observed by SDO/AIA satellite.rnIn addition, wavelet analysis will also be donernfor checking the stationarity of these two periods.
67
Mei Zhang
National Astronomical Observatory of China
Current helicity in large-scale photospheric magnetic fields and their solar cycle dependence
oral
The hemispheric sign rule of current helicity is examined for large-scale magnetic fields, extending to 60 degrees high in solar latitudes, at three different phases of solar cycle 23 and using three different instruments. The current helicity is calculated from the vector magnetic fields, derived respectively from the longitudinal full-disk magnetograms obtained by MDI on board SOHO as well as the KPVT and SOLIS at Kitt Peak of NSO. We have used the same technique introduced by Pevtsov and Latushko to retrieve the vector magnetic field but have applied a different method to calculate the current helicity. Our analysis strengths the evidences that the large-scale magnetic fields show clear and consistent current helicity pattern that follows the established hemispheric rule, that is, positive helicity sign in the southern hemisphere and negative helicity sign in the northern hemisphere. This hemispheric sign pattern presents everywhere in the global magnetic field, extending to 60 degrees high in solar latitudes, independent of the instruments and parameters used, and is evident at both solar maximum and minimum phases.
68
Mukul Kumar
Institute of Technology, Banaras Hindu University, Varanasi-221005, In
Analysis of an M-class Flare and Associated Eruption from NOAA AR 11045 Observed on 7 February 2010
oral
We present multi-wavelength observations of an M-class flare from NOAA AR11045 on 7 Feb. 2010, using space and ground-based observations from TRACE, STEREO, SoHO/MDI, EIT, Nobeyama Radio Heliograph and its associated eruption. We find a unique observational evidence for change in magnetic field configuration at flare site probably from dipolar to quadrapolar regime which results in its complexity and thus buildup of the flare energy. The change of magnetic field configuration seems to be associated with photospheric flows. This shows opposite vortices around the pair of opposite polarity spots at flare site. The negative polarity region, rotating counterclockwise, breaks positive polarity region into two parts. The bi-halved positive polarity is also rotating in the opposite direction in clockwise. This unique event eventually leads to the formation of flare energy. The STEREO-A/195 Å and STEREO-B/171 Å coronal images reveal that a flux tube is de-associated from the same site. SOHO/EIT 195 Å image, co-aligned with SOHO/MDI, shows coincidence with flare site, unique dynamics of spot pair, and eruption of flux tube at flare site. The formation of co-spatial bipolar radio contours at the same location probably also reveals the ongoing reconnection process above flare site and thus the acceleration of non-thermal particles with radio emission. The reconnection in the more complex magnetic field configuration at flare site, may also be responsible for the detachment of flux tube that further causes CME eruption with a speed of ~ 412 km/s.
69
N.Vasanthraju
Indian Institute of Astrophysics
Site characterization for the proposed National Large Solar Telescope in India
poster
Submitted by Prof.S.P.Bagare
70
Nagaraju Krishnappa
Max-Planck-Institute for Solar System Research
Small Sclae Chromospheric Velocity Structures
oral
We present the analysis of chromospheric velocity structures observed simultaneously in Hydrogen alpha and Ca II 8542 A lines. The data are a part of the full Stokes spectropolarimetric observations carried out in H-alpha and Ca II 8542 A lines using the SPINOR instrument at the Dunn Solar Telescope. The velocity structures we report here are the upflows surrounded by the downflows appearing similar to the velocity pattern associated with the photospheric granulation. The magnitude of up- and down-flows range from 2-4 Km/sec. Typical sizes of these structures are 5-6 arcseconds with the life time ranging from 7-15 minutes. Detailed analyses of velocities correspond to the bisectors at different line intensity levels suggest that these structures are confined in the lower to middle chromosphere. The above observed properties suggest the velocity structures we report neither correspond to granulation nor to supergranulation or to mesogranulation.
71
Namgyal Dorjey
Indian Institute of Astrophysics
Site characterization for the proposed National Large Solar Telescope in India
poster
Submitted by Prof.S.P.Bagare
72
Nandita Srivastava
Udaipur Solar Observatory, PRL, Udaipur
Estimation of arrival time of CMEs from STEREO observations
oral
One of the main objectives of the STEREO mission is to provide a 3D view of the solar corona from two vantage points. These are useful for estimation of true speeds and direction of propagation of Coronal Mass Ejections (CMEs) launched from the Sun. In particular for the CMEs that are directed earthwards, STEREO observations are expected to provide better estimaes of the arrival times of the CMEs at the earth as compared to the those derived from a single spacecraft observation. In this paper, I will present observations of a few earthward directed CMEs obtained by SECCHI suite of instruments aboard STEREO spacecraft namely EUVI disk imager, COR1 and COR2 coronagraphs of the SECCHI package. The observations of CMEs were reconstructed in 3D using Tie-Point reconstruction and Forward Modeling techniques, and their kinematics were studied. The results of this study shows that it has a direct bearing on the arrival time of the CMEs and hence prediction of the space weather. For this purpose, we consider a simplified model of spherically expanding CME front with a self-propagating centre. We find that arrival times estimated by STEREO observations assuming this model are in better agreement with the actual arrival time.
73
Nat Gopalswamy
NASA Goddard Space Flight Center
Coronal Mass Ejections and their Heliospheric Consequences
invited
Coronal mass ejections (CMEs) have been recognized as the most energetic phenomenon in the heliosphere, deriving their energy from the stressed magnetic fields on the Sun. The Solar and Heliospheric Observatory (SOHO) mission has accumulated a wealth of information on CMEs with unprecedented extent, clarity, and uniformity. The CME data base has been useful in confirming results from past missions and obtaining a number of new results on the initiation, propagation, and heliospheric consequences of CMEs. This paper highlights some of the recent results on the morphological, physical, and kinematic properties of CMEs observed during solar cycle 23. White-light signatures of CMEs and their utility in inferring coronal magnetic fields near the Sun will be discussed. Presence of coronal holes near eruption regions have been shown to significantly modify the trajectories of CMEs. New results on the interaction of CMEs with large-scale structures such as coronal holes and other CMEs will be presented. Finally, the CME consequences in the heliosphere such as interplanetary shocks, type II radio bursts, energetic particles, geomagnetic storms, and cosmic ray modulation will be discussed.
74
Nazia Afreen Ahmed
Indian Institute of Astrophysics, Kodaikanal
None
poster
None
75
Neeharika
Indian Institute of Astrophysics, Bangalore
Cycle 23-24 prolonged solar minimum recorded in Almahata Sitta meteorite
oral
Galactic Cosmic Rays (GCR) produce a large number of radioactive and stable isotopes in meteoroids while they are exposed in the interplanetary space before they fall on the Earth. The solar magnetic field modulates the GCR flux and hence the induced radioactivity is anti-correlated with the sun spot number. Asteroid 2008 TC3 fell in Sudan on 7 October 2008.Two months later, many meteorite fragments were recovered from the Nubian desert of Sudan.The orbit of the meteoroid is known to have low inclination (i=2.54o) and apogee in the inner asteroid belt (a = 1.7AU) and it monitored the cosmic rays in the near earth space.Six gamma emitting radionuclides (46Sc, 57Co, 54Mn, 22Na, 26Al, and 60Co)in the largest ureilitic fragment (Almahata Sitta#15) weighing 75 grams were measured using a sensitive gamma-ray spectrometer at the Laboratory of Monte dei Cappuccini in Torino,Italy.The activities of 60Co (27.7 ± 0.8 dpm/kg), produced mainly by neutron capture in cobalt, and of 26Al (62.1 ± 0.8 dpm/kg) indicate that fragment #15 was located at a depth within 27 and 55 cm inside the 1.5-2 meter radius asteroid.The 22Na/26Al activity ratio is higher than expected(1.6) for the average cosmic ray flux.The sun spot minimum before cycle 24 was unusually long and took about 7 years to attain a minimum value only by end of 2009. High 22Na activity as well as the activity ratio 22Na/26Al of 1.7 can be understood in terms of this prolonged sun spot minimum before the fall of the meteorite. rnrn
76
Neeharika Sinha
Indian Institute of Astrophysics, Bangalore
Spectro-polarimetry with the NLST: Evaluation of Seeing Induced Crosstalk Errors
poster
The measurement of complete polarization state of solar line profiles is required to infer the strength and orientation of magnetic fields at the solar surface. In order to have good spatial and spectral resolution in the measurements, a large aperture solar telescope such as the proposed NLST in combination with array detectors is required. However, the spatial resolution in such measurement is affected by atmospheric seeing. Adaptive optics, which is an integral part of any large telescope, will minimize such effects. rnIn polarimetry, crosstalks are defined as the intermixing of the four Stokes vector I, Q, U and V as a result of an imperfect measurement process. The sources of this error are the incomplete calibration of the telescope-polarimeter system and the fluctuation in the signal due to atmospheric seeing. The former can be estimated by calibrating accurately the telescope- polarimeter system using calibration optics placed very close to the prime focus. In order to understand the cross-talk produced by the latter, we quantitatively studied the effect of seeing on the polarimetric measurement process. We analyze the atmospheric induced crosstalk errors among the Stokes I, Q, U, and V parameters using the formalism already developed by Lites [1987]. The power spectrum of the Fried’s parameter r0 obtained from the solar differential image motion monitor (SDIMM) at Merak site, the candidate site for proposed NLST,is used in this formalism.The preliminary results and the implications of these results for the spectro-polarimetry of NLST will be discussed in this paper.
77
Neeraj Singh Bankoti
Department of Physics Kumaun University Nainital
North-south asymmetry of different solar activity features during solar cycles 20-23
poster
This paper presents the comparative study of north-south asymmetry, cumulative north–south asymmetry and cumulative difference indices of sunspot areas, solar active prominences (at total, low (≤400) and high (≥500) latitudes) and Hα solar flares during solar cycles 20 to 23. Three different statistical methods are used to obtain the north-south asymmetry of different solar activity features. Hemispherical distribution of activity features shows the dominance of activities in northern hemisphere for solar cycle 20 and in southern hemisphere for solar cycles 21–23 excluding solar active prominences at high latitudes. Cumulative difference index of solar activity features in each solar cycle is observed at the maximum of the respective solar cycle suggesting a cyclic behavior of approximately one solar cycle length. Asymmetric behavior of all activity features except solar active prominences at high latitudes hints at the long term periodic trend of eight solar cycles. North–south asymmetries of SAP(H) express the specific behavior of solar activity at high solar latitudes and its behavior in long-time scale is distinctly opposite to those of other activity features. Our results show that in most cases the asymmetry is statistically highly significant meaning thereby that the asymmetries are real features in the N-S distribution of solar activity features.
78
Ning Zongjun
Purple Mountain Observatory
Chromospheric Evaporation Seen at HXR
oral
Based on the standard model of solar flare, chormospheric evaporation is an basic process. In the documents, there are many obervational evidences of this process seen at radio and EUV. In this talk, we give the evidences seen at the hard X-rays.
79
O Prakash
School of Physics Madurai Kamaraj University
Characteristics of Type II Bursts and Their Relation to Flares and CMEs
poster
Investigations on the characteristics and relationships between type-II radio bursts appearing in the metric (m) and decameter-to-hectometer (DH) wavelength ranges and associated flares and CMEs observed during the period of 2000-2005. The sample is divided into two populations: Group I, flare onset time occurred before the onset time of CME; Group II, flare onset time occurred after the onset time CME. Our analysis consists of three steps: i) characteristic properties of m-and DH-type-II bursts; ii) the relation between the type-II bursts pairs associated with flares and CMEs and iii) the relation between the flares and CMEs of Group I and Group II events. The main results will be presented in this paper.
80
P. F. Chen
Department of Astronomy, Nanjing University
EIT Waves and Coronal Mass Ejections
invited
EIT waves are one of the most important discoveries in solar physicsrnduring the SOHO era. They appear as bright fronts in the EUV differencernimages, propagating with a typical velocity of 200-400 km/s. They arernfound to be intimately associated with coronal mass ejections (CMEs).rnThe research on EIT waves is not only important for the understandingrnof this intriguing phenomenon, it can also shed light on the underlyingrnphysics of CMEs. However, there are strong debates among the communityrnregarding the nature of EIT waves. It is widely believed that EIT wavesrnare fast-mode waves. However, such a model was challenged by variousrnobservations. In this talk, I will review the many faces of EIT wavesrnrevealed by SOHO, STEREO, and recent SDO satellites, which cannot berninterpretted in terms of fast-mode waves, and comment on the otherrnalternative models, with the emphasis on our fieldline stretching model.rnThe implication to the CME physics is also discussed.
81
P. Janardhan
Associate Professor, Physical Research Laboratory, Ahmedabad, India
Solar Polar Fields During Cycles 21-23: Correlation with Meridional Flows
oral
We have examined polar magnetic fields for the last three solar cycles, viz. Cycles 21, 22, and 23 using NSO/Kitt Peak synoptic magnetograms. In addition, we have used SOHO/MDI magnetograms to derive the polar fields during Cycle 23. Both Kitt Peak and MDI data at high latitudes (78° – 90°) in both solar hemispheres show a significant drop in the absolute value of polar fields from the late declining phase of the Solar Cycle 22 to the maximum of the Solar Cycle 23. We find that long-term changes in the absolute value of the polar field, in Cycle 23, are well correlated with changes in meridional-flow speeds that have been reported recently. We discuss the implication of this in influencing the extremely prolonged minimum experienced at the start of the current Cycle 24 and in forecasting the behavior of future solar cycles.
82
P. Venkatakrishnan
Udaipur Solar Observatory, Physical Research Laboratory
The research and development activities of the Udaipur solar observatory revolve around the central theme of solar activity and solar eruptive processes. Helioseismology is used as a tool to dig into the sub-surface origins of eruptions. Surface magnetic field is measured to monitor magnetic energy storage and evolution of the potential triggers of the eruptions. Above the surface, chromospheric and coronal phenomena are used to predict the geoeffectiveness of these eruptions. A combination of analyses of archived data, mathematical modeling and construction of sophisticated instruments is employed to achieve the desired goals. Some of these science discoveries are briefly enumerated in this talk. This is followed by the description of a few specific results obtained in recent times and a brief progress report on the observatory?s 50 cm Multi Application Solar Telescope (MAST) project. Finally, the future directions will be outlined.
83
P.K. Manoharan
Tata Institute of Fundamental Research (NCRA-TIFR)
Solar Cycles 22 and 23: 3-D Evolution of Heliosphere
invited
A large amount of IPS measurements obtained from the Ooty Radio Telescope has been employed to study the 3-D evolution of the solar wind during the period 1985–2010. The large-scale features of the inner heliosphere show remarkable difference between solar cycles 22 and 23. The results indicate that (1) at the minimum phase of cycle 23, the extent of low-speed region along the equatorial belt of the heliosphere has been considerably wider than that of the previous cycle; whereas the high-speed regions of the solar wind have shrunk towards the poles in contrast to their extensions from poles to about +/-30 degree down to low latitudes at the similar phase of cycle 22; (2) the minimum phase of cycle 23 has also experienced a low level of coronal density turbulence and the scattering diameter of the corona with respect to the Sun has decreased steadily from about the year 2003, i.e., during the declining phase of the activity. The above peculiar properties of the solar wind associated with cycle 23 are compared with the magnetic field distributions on the Sun and in the interplanetary medium.
84
Pankaj Kumar
Korea Astronomy and Space Science Institute (KASI)
On the Triggering of M-Class Solar Flare due to Loop-loop Interaction in AR NOAA 10875
oral
We analyze multi-wavelength data of an M7.9rn/1N class solar flare which occurred onrn2006 April 27 in AR NOAA 10875 due to the interaction of two loop systems. GOESrnsoft X-ray and TRACE 19rn5 Å image sequences reveal the loop–loop interaction and thernformation of “X” points with converging motion (∼30 km/s), which provides an evidencernof progressive reconnection and flare maximization in the active region. The absence ofrntype III radio bursts during this time period indicates no opening of magnetic field linesrnduring the flare, which indicates that the change of field line orientation occurred onlyrnduring the loop–loop interaction and reconnection process. The Ondrejov dynamic radiornspectrum shows an intense decimetric (DCIM) radio burst (2.5–4.5 GHz) during the flarerninitiation as a signature of the particle acceleration from the reconnection site duringrnloop–loop interaction. The double-peak structures at 4.9rn and 8.8 GHz also provide thernmost likely evidence of the loop–loop interaction at the flare site in the active region.rnRHESSI hard X-ray images reveal the loop-top and footpoint sources of therncorresponding two loop systems that are the current-carrying flux tubes with resultantrnopposite magnetic fields and net force of attraction, and their coalescence occur duringrnthe flare maximum. In conclusions, the shear motion of one of the footpoint of smallerrnloop may be responsible for the flare energy buildup and its release due to the loop–looprninteraction.rn
85
Piyali Chatterjee
Nordita, Stockholm
Alpha effect due to magnetic buoyancy instability.
oral
A strong toroidal field can exist in the form of a magnetic layer in the overshoot region below the solar convection zone. This motivates a more detailed study of the magnetic buoyancy instability with rotation. We calculate the alpha effect due to helical motions caused by a disintegrating magnetic layer in a rotating density-stratified system with angular velocity Omega making an angle theta with the vertical. We also study the dependence of the alpha effect on theta and the strength of the initial magnetic field. A turbulent EMF due to the correlations of the small scale velocity and magnetic field is generated. We use the test-field method to calculate the transport coefficients of the inhomogeneous turbulence produced by the layer. We show that the growth rate of the instability and the twist of the magnetic field vary monotonically with the ratio of thermal conductivity to magnetic diffusivity. The resulting alpha effect is inhomogeneous and increases with the strength of the initial magnetic field. It is thus an example of an "anti-quenched" alpha effect.
86
Prabhu K.
Indian Institute of Astrophysics
Site characterization for the proposed National Large Solar Telescope in India
poster
Submitted by Prof.S.P.Bagare
87
Prabhu Ramkumar
IIA
poster
88
Qingmin Zhang
Nanjing University
Two types of Magnetic Reconnection in Coronal Bright Points and the Corresponding Magnetic Configuration
oral
Coronal bright points (CBPs) are long-lived small-scale brightenings in the lower corona. They are generally explained by magnetic reconnection. However, the corresponding magnetic configuration and how the reconnection proceeds are not well understood. We carry out a multi-wavelength analysis of two neighboring CBPs near the center of the solar disk observed by the X-ray Telescope (XRT) aboard the Hinode satellite and the Extreme Ultraviolet Imager (EUVI) aboard the Solar TErrestrial RElations Observatory (STEREO) on 2007 March 16. It is seen that the soft X-ray (SXR) light curves present quasi-periodic flashes with a period of $sim 1$ hr in addition to the long-lived mild brightenings, suggesting that there might be two components, one is the gentle brightenings, and the other is the CBP flashes. It is found that the strong flashes of the northern CBP are always accompanied by SXR jets. The potential field extrapolation based on the Global Oscillation Network Group (GONG) magnetograms indicates that both CBPs are covered by a dome-like separatrix surface, with a magnetic null point above. We propose that the repetitive CBP flashes, as well as the recurrent SXR jets, result from the null-point impulsive reconnection, whereas the long-lived brightenings are due to the interchange reconnection along the separatrix surface. The latter process can also account for the smaller Doppler velocities generally measured in CBPs. While the EUV observations at hot lines, e.g., 284 {AA}, resemble the SXR appearance, the 171 {AA} and 195 {AA} channel.
89
R. Kariyappa
Indian Institute of Astrophysics
First Results on Solar Irradiance Variability from PROBA2/LYRA
poster
The Sun is the primary source of energy responsible for governing both the weather and climate of Earth. For that reason alone one would expect that changes in the amount and type of energy Earth received from the Sunrncould alter weather and climate on the Earth. The variations in the UVrnirradiance are produced by surface manifestation of solar magnetic activity. Considering the variations in the solar UV flux may causernsignificant changes in the Earth's climate, understanding the physicalrnorigin of UV irradiance changes is an extremely important issue in Solarrnand Space Physics.rnrnWe have analysed the time series of irradiance measurements from PROBA2/LYRArnin Channel 3 (HeII 304 A) and full-disk integrated intensity values observedrnwith PROBA2/SWAP 174 A. We found that there is good correlation between the LYRA irradiance values (observed Sun as a Star) and spatially resolved full-disk intensityrnvalues of SWAP 174 A. This clearly explains that the LYRArnirradiance variations are due to the various magnetic features which are contributing significantly.rnThe detailed analysis and the important results will be discussed in this paper.
90
R. Kariyappa
Indian Institute of Astrophysics
Coronal Rotation from XBPs Observed with Hinode/XRT
poster
We have selected a large number of XBPs over synoptic soft X-ray full-disk images observed using Al-Mesh with X-Ray Telescope (XRT) onboard the Hinode spacecraft duringrnJuly-December, 2008. We have analyzed the full-disk imagesrnusing SSW in IDL. We used the tracer method to identify andrntrace the passage of XBPs over the solar disc with the help of overlaying grids. We also obtained the position (Latitude and Longitude), size & brightness information for XBPs using tracer method as a function of time and thus calculated siderealrnangular rotation rate of corona at different latitudes. We have compared the rotation rate with latitude, size and brightness of XBPs.rnrnThe important results derived from these analysis are: (i)rnthe rate with which solar corona rotates differentially like the photosphere and chromosphere; (ii) the larger XBPs show a lower sidereal angular rotation rate, the smaller XBPs exhibit higher rotation rate, similar to sunspots; and (iii) it is notrnclear on brightness of XBPS with coronal rotation rate, needs further investigation & it is in progress.
91
R. Ramesh
Indian Institute of Astrophysics
Radio observations of the solar corona witrh the Gauribidanur radioheliograph
oral
Several interesting results on CMEs, flares, coronal magnetic field have been obtained with the Gauribidanur radioheliograph during the last solar cycle. The results and their usefulness in understanding the dynamics of the solar corona will be presented.
92
Rajendra B. Singh
Indian Institute of Astrophysics
Site characterization for the proposed National Large Solar Telescope in India
poster
Submitted by Prof.S.P.Bagare
93
Rajmal Jain
Physical Research Laboratory
Relationship between Flare associated CMEs and SEPs
oral
We present investigation of the 50 flare associated CMEs observed during sunspot cycle 23 and 24 in context to their capability to producing solar energetic particles (SEPs). We consider studying these powerful events, for while the major processes involved are now known, the basic physical mechanisms of energy release and particle acceleration are less understood. The X-ray observations of the flares under investigation have been employed from SOXS, RHESSI, BATSE and GOES missions, while we use the CME images taken by LASCO/ SOHO and STEREO. For measurements of SEPs we employ GOES, ACE and WIND observations. In order to estimate the magnetic field parameters we use MDI/ SOHO observations. Detailed analyses revealed that in most of events (75%) the opposite polarities of pre-existing region as well as the EFRs show flux cancellation. We propose that flare-CME activities were probably caused by the magnetic reconnection in the lower atmosphere driven by photospheric convergence motions. The slow low-layer magnetic reconnection may be responsible for the storage of magnetic free energy in the corona and the formation of a sigmoidal core field or a flux rope leading to the eventual eruption. We found that the CMEs associated with the flares revealing soft-hard-hard X-ray spectrum produce significant SEPs at energies >10 MeV. Based on the analysis we propose a qualitative model, and conclude that the mass ejections, filament eruption, CME and subsequent flare, and associated SEP were connected with one another and should be regarded within the framework of a solar eruption.
94
Ram Ajor Maurya
PRL, Ahmedabad
Variations in High Degree p-mode Parameters with Flare Activity
oral
We have determined the characteristic properties of the high degree p-modes by applying the ring diagram technique to several flaring and non-flaring active regions of solar cycle 23. Strong evidence of substantial increase in mode amplitude is found from comparison of the pre- to the post-flare phases of energetic flares. We have also found statistically significant association between the mode energy and flare energy. We shall discuss variations in p-mode parameters (mode amplitute, frequency, etc.) in some ARs having long lifetimes, covering two or three Carrington rotations.
95
Ramesh Chandra
Department of Physics, DSB campus, Kumaun University, Nainital, Uttar
Study of Solar Flares and Filament Interaction from NOAA 10501 on 20 November, 2003
oral
We analyze two homologous flares from active region(AR) NOAA 10501 on 20 November, 2003, that exhibit four ribbons each. A new emerging bipole in the center of the region has a peculiar evolution. The negative polarity breaks in a few pieces and a part of it rotates around the positive polarity. That is the site of the core of both flares. The evolution of the ribbons suggests that the first eruption is triggered by ``tether cutting'', whereas the second one is consistent with the ``magnetic breakout'' model. Using a linear force-free extrapolation of the photospheric magnetic field the four ribbons have been interpreted as being the footpoints of loop systems during reconnection. The region has a main quadrupolar configuration and the ribbons fit well with the intersections of Quasi-Separatrix Layers with the chromosphere.rnrnAnother interesting feature of our observations is the interaction of two filaments elongated in north-south direction. The filaments merge at their central parts and afterwards change their orientation to the east-west direction. We test these observations using a three-dimensional (3D) zero β magnetohydrodynamic (MHD) simulation with an initial condition for the magnetic field based on a modified version of the cronal flux rope modeled by Titove and Demoulin (1999)
96
Robert CAmeron
Max Planck Institute for Solar System Research
The evolution of the Sun's large scale magnetic field
invited
We use the surface flux transport model to study the evolution of the Sun's surface magnetic field. Special attention is paid to ensure that the source term has the observed statistical properties. In particular, we include the recently discovered cycle variations of Joys law (Dasi-Espuig et al, 2010 A&A 518 A7).We find that the model is able to reproduce the observationally inferred heliospheric magnetic field strengths, and that the polar fields at the end of a cycle are correlated with the strength of the subsequent cycle
97
Robert Erdelyi
SP2RC, School of Mathematics and Statistics, University of Sheffield
Alfven waves in the solar atmosphere: A magneto-seismology approach
invited
The latest satellite and ground-based observations have provided a wealth of evidence of waves and oscillations present in the solar atmosphere. Our understanding of the structure and dynamics of the solar atmosphere has been considerably changed in light of the high spatial and time resolution observations (e.g. DST/ROSA, IBIS, CoMP, STT/CRISP; SOHO, TRACE, STEREO, Hinode, SDO, etc.) allowing us to perform sub-resolution magneto-seismology of MHD waveguides. Here we will concentrate on the role of Alfven waves, and will discuss first the latest status of the sometimes controversial observations of these particular, and fundamentally important waves.rnrnNext, we show our latest theoretical interpretations of the detected Alfven wave and oscillatory phenomena within the framework of MHD. The photospheric origin and generation mechanism of these peculiar waves is addressed numerically. We show how Alfven waves penetrate into the chromosphere, transition region or even into the corona. The coupling role of the magnetic field for Alfven waves and oscillations between the solar interior and atmosphere will be addressed briefly. Finally, in light of our theoretical studies, we conclude how solar magneto-seismology evolved with Alfven waves and how the new observational data on Alfven waves can be used for a more accurate atmospheric diagnostics, including such important aspects as e.g. determining (i) the extent of the force free (or not!) nature of the solar atmosphere, (ii) the geometry, (iii) fine structure, and (iv) even the heating mechanism(s) of coronal loops.
98
ROHINI V.S.
govt.science college ,bangalore-1.
solar irradiance modelling
poster
composite total solar irradiance(CTSI),sun spot area(SSA)are always anticorrelated,which can be varified on different time scales of solar differential rotation periods like 27,28...31 days.rnamong them contribution by 27 day rotation is significant.rnso 27 day averaged CTSI & SSArnare studied simulteneously by plotting them together.rnthe phase lags(measured in days ,called delays)between SSA maxima & CTSI minima are noted down.rnfurther charecterstics of these delays are studied .rnit is found that for 27dayrnaveraging the delays vary from -230 to +230 days,with maxima at 13.5 days,minima at -230 & +230 days.rnboth maxima & minima predictsrnthat FeII is actively participating in such delay process.this hints that stopping or delaying of solar radiations are due to developing or decaying FEII flux tubes assosciated with sunspots.rnthe delays so determined can be suitably combined with other 27 day averaged parameters like 27SSA,27CTSI,SOLAR MAGNETIC FIELD(27B)etc for delayed events such that solar irradiance (at 1AU) can be modelled with an error limit of0.04- 0.05% wrt 1AU rawctsi. rnusing raw data of solar cycle 21,22,23 about 6 models are developed.
99
Ronglin Jiang
Department of Astronomy, Nanjing University
FAN-SHAPED JETS IN THREE-DIMENSIONAL RECONNECTION SIMULATION AS A MODEL OF UBIQUITOUS SOLAR JETS
oral
Magnetic reconnection is a fundamental process in space and astrophysical plasmas in which the oppositely directed magnetic field changes its connectivity and eventually converts its energy into kinetic and thermal energy of the plasma. Recently, ubiquitous jets (for example, chromospheric anemone jets, penumbral microjets, umbral light bridge jets) have been observed by the Solar Optical Telescope on board the satellite Hinode. These tiny and frequently occurring jets are considered to be a possible evidence of small-scale ubiquitous reconnection in the solar atmosphere. However, the details of three-dimensional (3D) magnetic configuration are still not very clear. Here, we propose a new model based on 3D simulations of magnetic reconnection using a typical current sheet magnetic configuration with a strong guide field. The most interesting feature is that the jets produced by the reconnection eventually move along the guide field lines. This model provides a fresh understanding of newly discovered ubiquitous jets and moreover a new observational basis for the theory of astrophysical magnetic reconnection.
100
S. Krishna Prasad
Indian Institute of Astrophysics
Propagating intensity disturbances in polar corona as seen from AIA/SDO
oral
Polar corona is often studied and is very important for its connection to the acceleration of fast solar wind. During solar minimum, it is structured into several bundles of open magnetic field lines with dense and cool plasma than its surroundings. These are called plumes and the lanes between two plumes are called interplume regions. We explored several such plume and interplume regions using the data from AIA on-board SDO and found propagating quasi-periodic disturbances of periodicities ranging from 10 min to 30 min, in almost all the locations. We see these disturbances travelling as far as 250 arcsec off-limb, in a few cases. The propagation speeds are ranging from 100 km/s to 170 km/s. It is observed that the average speeds are different in different passbands and also higher in interplume regions than that of plume regions. We suggest that these disturbances are slow magneto-acoustic waves.
101
S. P. Bagare
IIA, Bangalore
Influence of the abmient magnetic field configuration on the physical properties of sunspots
oral
We have studied a large number of sunspots using the digitized photoheliograms of the Kodaikanal Observatory and the magnetic field observations reported by the Academy of Sciences, Leningrad, for the maximum phase of the solar cycle 21 in the years 1978 - 82. It turns out that the spots respond dynamically to the magnetic bipolarity of the ambient fields, in the form of neighbouring spots and strong pores. The changes are readily observed in the relative area of the spot penumbra. We report the main results obtained so far. It also appears that the results obtained can be used to explain the absence of Wilson Effect in a significant proportion of sunspots, a phenomenon reported by most of the authors who studied the Effect earlier.
102
S. PRASANNA SUBRAMANIAN
MADURAI KAMARAJ UNIVERSITY COLLEGE, AUNDIPATTI, THENI DISTRICT
Study of Interacting CMEs and DH Type II Radio Bursts
poster
Abstract: Some Coronal Mass Ejections(CMEs) are classified as interacting CMEs and it is important to understand their physical and kinematic characteristics. We have identified a set of interacting CMEs and their associated DH type II radio bursts are collected. Our study is to compare various parameters like speed, duration, central position angle and acceleration of CMEs. The properties of the DH type IIs and the relation with the CMEs are examined in this paper. The results from this analysis will be presented here.
103
S.M. Chitre
Mumbai University
The advent of Solar Physics in India may be traced to the study ofrnspectrumrnof the Sun.In fact,the spectroscopic & photographic techniques used forrnobserving the total solar eclipse of 1868 played a major role in therndiscovery of a new element by the French astronomer ,Janssen which wasrnaptlyrnnamed helium by the co-discoverer Lockyer.During his post-eclipse stay inrnIndia,Janssen designed the spectrohelioscope which facilitated dailyrnobservations of the Sun.rnThe establishment of a small observatory at Madras in 1786 devoted largelyrnto positional astronomy served as the reference meridian for the GreatrnTrignometrical Survey of India and also enabled the compilation of arncatalogue of southern stars.A century later on the recommendation of arncommittee headed by Lord Kelvin a solar observatory was set up in 1893 inrnKodaikanal in the Palni hills of south India.The arrival of JohnrnEvershed atrnthe observatory in 1907 marked the beginning of an active research era inrnsolar physics in India.The post-independence years saw the establishment ofrnthe Uttar Pradesh State observatory at Naini Tal, the Udaipur SolarrnObserbatory hosting one of the six automated observating stations of thernGONG network,the OOTY & GMRT facilities,Gauribidanur Radio Heliograph andrnthe solar radio telescope at Rangapur observatories of OsmaniarnUniversity...rnrnOver the past 4 decades or so,theoretical solar researches have beenrnpursuedrnat a number of observatories,research institutes and university departmentsrncovering a wide range of areas including physics of the solar interiorrnusingrnthe accurately measured helioseismic data,solar neutrino puzzle,solarrnmagnetism & solar dynamo problem,study of velocity & magnetic oscillationsrnin the photosphere,structure and dynamics of magnetic flux tubes,sunspotsrnand active region complexes with the associated transient events,radiornobservations of flares,bursts,prominences and coronal massrnejections,physical conditions in the chromosphere,corona and the coronalrnholes and mechanisms for heating the outer layers of the Sun,solar wind &rnthe interplanetary medium,solar irradiance variation and space weather
104
S.M.Fathima Khyrun
Indian Institute of Astrophysics
none
poster
none
105
S.P. Rajaguru
Indian Institute of Astrophysics
Local helioseismology and near-surface magnetohydrodynamics
oral
While the strong thermal and magnetic effects of near-surface layers of sunspots rnon the sound waves render the conventional seismic tomography inadequate to determinerntheir 3-D structure, signatures due to probable perturbations associated with rnlarge scale magnetic and flow structures deep in the convection zone (the tachocline)rnrequire devising new ways of boosting the sensitivity of helioseismic techniques.rnOn the former case, I present and discuss newly identified problems and issues thatrnthe near-surface magnetohydrodynamics hosts through a complex interplay of radiativerntransfer, measurement issues and MHD wave processes. On the latter, I discuss tests on rnimprovements in deep-focus measurement scheme and those achievable from arntwo-vantage-point observations, i.e. spacecrafts having an optimum coverage of the rnsurface of the Sun to follow the deeper plunging long wavelength waves more efficientlyrnand without projection effects.
106
S.T.KUMARA
Bangalore University & Auden Technology and Management Academy
First Results on Solar Irradiance Variability from PROBA2/LYRA
poster
The abstract of this paper has been already submitted by my guide, Dr.R.Kariyappa,Indian Institute of Astrophysics,Koramangala,Bangalore-560034.
107
Sajal Kumar Dhara
Indian Institute of Astrophysics
None
poster
None
108
Sangita K. Padhy
Indian Institute of Astrophysics
Site characterization for the proposed National Large Solar Telescope in India
poster
Submitted by Prof.S.P.Bagare
109
Satish Chandra
PPN College, Kanpur - 208 001
Differential Coronal Rotation and Solar Activity
oral
The rotation of the solar rotation is still a matter of great interest because of its unique latitudinal and height profiles and temporal and spatial variations. In the last decades, the observations of the solar coronal rotation period have shown variations between rigid rotation to differential rotation across the latitude. The purpose of present study is to investigate the latitudinal variation in the coronal rotation by using the Nobeyama Radio Heliograph (NoRH) at 17 GHz. The time series bins are formed on different latitude regions of the solar full disc (SFD) radio images at 17 GHz, which extend up to +/- 60 degree in both the hemisphere. The coronal sidereal rotation rate as a function of latitude for each year, extending from 1999-2005 for radio images are obtained. The coronal electron density model is used and it is estimated that the radio emission at 17 GHz would be originating from a height ~1.2 × 10^4 km above the photosphere. The present analysis reveals that the equatorial rotation rate of the corona is comparable to the photosphere and the chromosphere, However, at the higher latitudes, the corona rotation quite differently than the photosphere and chromosphere. The latitude differential obtained by radio images is quite variable throughout the period of the study. The equatorial rotation period and its latitude dependent differential rate seem to vary almost systematically with sunspot numbers which indicates its dependence on the phases of the solar activity cycle.
110
SAVITHRI DEVI E
MAHATMA GANDHI UNIVERSITY,KOTTAYAM,KERALA
STABILITY OF KINETIC ALFVEN WAVES IN THE SOLAR WIND DUE TO HEAVY IONS OF COMETARY ORIGIN
poster
The ionisation of neutral atoms and molecules as they stream away from a comet corresponds to the introduction of a free energy source into the solar wind. A type of heavy ion that has been observed in a number of cometary environments is oxygen (O+).rn If there is a nonzero angle between the solar wind flow velocity, Vsw, and the average interplanetary magnetic field, B0, then the introduction of cometary ions initially leads to a ring-beam distribution that can excite a number of instabilities.rn We, therefore, study the stability of the kinetic Alfven wave in a plasma of hydrogen, oxygen and electrons. Each species has been modeled by drifting ring distributions in the direction parallel to the magnetic field; the perpendicular ring is simulated with a loss-cone type distribution obtained through the subtraction of two Maxwellians with different temperatures.rn We find that for Doppler shifted frequencies less than the hydrogen ion gyro- frequency, the growth rate of the kinetic Alfven wave increases with increasing propagation angles and oxygen ion densities. On the other hand, for Doppler shifted frequencies less than the oxygen ion gyro-frequency, the growth rate is independent of the oxygen ion densities.
111
Shantikumar Singh Ningombam
Indian Institute of Astrophysics, Bangalore
Site characterization for the proposed National Large Solar Telescope in India.
poster
Submitted by Prof.S.P.Bagare
112
Siraj Hasan
Indian Institute of Astrophysics
The National Large Solar Telescope NLST will be a state-of-the-art 2-m rnclass telescope for carrying out high-resolution studies of the solar rnatmosphere. Sites in the Himalayan region at altitudes greater than rn4000-m that have extremely low water vapor content and are unaffected by rnmonsoons are under evaluation. This project is led by the Indian rnInstitute of Astrophysics and has national and international partners. rnIts geographical location will fill the longitudinal gap between Japan rnand Europe and is expected to be the largest solar telescope with an rnaperture larger than 1.5 m till ATST and EST come into operation.rnrnNLST is an on-axis alt-azimuth Gregorian multi-purpose open telescope rnwith the provision of carrying out night time stellar observations using rna spectrograph at the Nasmyth focus. The telescope utilizes an rninnovative design with low number of reflections to achieve a high rnthroughput and low polarization. High order adaptive optics is rnintegrated into the design that works with a modest Fried's parameter of rn7-cm to give diffraction limited performance. The telescope will be rnequipped with a suite of post-focus instruments including a rnhigh-resolution spectrograph and a polarimeter.rnrnThe detailed concept design of the telescope has been finalized and the rnproject awaits formal clearance fromrnthe Government of India.rn
113
Soyoung Park
Seoul National University
FISS Observations of Chromospheric Brightening Associated with CMFs
oral
Cancelling magnetic features (CMFs) are likely to be a result of magnetic reconnection in the lower atmosphere. CMFs are often related with chromospheric phenomena such as brightening or jets. In order to observe the fine-scale and highly dynamical structures in the chromospheres, Fast Imaging Solar Spectrograph (FISS) was developed and installed at 1.6 m New Solar Telescope at Big Bear Solar Observatory. This FISS records spectral lines at two spectral bands, the H-alpha and the Ca II 8542, simultaneously. Using the data taken from the observations on 2010 July 16 we have studied several chromospheric brightening associated with magnetic elements including CMFs. As a result, we obtained an important result that the Doppler motion of chromospheric features above a CMF changed from redshift to blueshift. The duration of the Doppler shift change in the CMF is very short, being less than 2 minutes. This unexpected result on the Doppler shift associated with the CMF could not be explained by any of preexisting pictures of CMFs.
114
Sreejith Padinhatteeri
University of Calicut /ISRO Satellite Center.
Formation of penumbra on sunpots.
oral
The physical mechanisms that drive the formation and evolution of small scale structures on a sunspot, like penumbra, are not yet fully understood. It is important to study the formation and evolution of these small scale magnetic structures to understand the physics of sunspots in particular and magnetic activities of the Sun in general. We used different data sets; one set of high resolution observation using Dunn solar telescope (DST), and multiple data sets of low resolution observations from SOHO-MDI to study penumbral formation in different sunspots. Our analysis suggest that, it is the change in magnetic flux value of the umbra, around which the penumbra forms, that plays a major role than the magnetic flux of the whole active region. We also investigate the effect of the rate of increase in magnetic flux on the penumbral formation.
115
Su-Chan Bong
Korea Astronomy and Space Science Institute
Physical Properties of Untwisting Chromospheric Surges of AR 10930
poster
We report untwisting chromospheric surges of AR 10930. Hinode Solar Optical Telescope (SOT) observed AR 10930 on the west limb continuously from 11:21 UT December 18 to 09:58 UT December 19, using the Ca II H broadband filter. During the observation, rise and fall motion accompanying rotation appeared recursively. There occurred a total of 14 surges at AR 10930 over 17 hours. The average duration was 45 minutes, and the average width, and length were 8 Mm, and 39 Mm, respectively. The dynamic properties including number of turns from the rise to the fall, the axial speed and acceleration are also analyzed. We speculate that the surges occurred by recursive reconnections between the twisted prominence and large untwisted flux tube.
116
Subhash Kaushik
Jiwaji University
Solar wind Transients and Disturbed Geomagnetic Field Conditions
poster
In the present investigation we have analyzed the solar wind transients and their consequences on geomagnetic field variation. These solar / interplanetary transients are large scale structures containing plasma and magnetic field expelled from the active regions of solar atmosphere. We have studied the Bi-directional Electron Heat Flux (BEHF) Events. These are the fast magnetized plasmoids moving away from the Sun in to interplanetary space. As they come to interplanetary medium the interplanetary magnetic field drape around them. This field line draping was thought as possible cause of the characteristic eastward deflection and giving rise to complex geomagnetic activities. In this paper a systematic study has been performed to analyze these BEHF events occurred during solar cycle 23, by dividing them in two categories 1. Associated with coronal holes (CH) and 2. Non - Associated with coronal holes. In this work we used hourly values of IMF data obtained from the NSSD Center. The analysis mainly based on looking into the effects of these transients on earth’s magnetic field. The high-resolution data IMF BZ and solar wind data obtained from GOES satellite was available during the selected period. Dst and Ap are taken as indicator of geomagnetic activities. It is found that Dst index, solar wind velocity, proton temperature and the Bz component of magnetic field have higher values and increase just before the occurrence of these events. Larger and varying magnetic field mainly responsible for producing the short-term changes are observed during the BEHF events associated with coronal holes.
117
Sung-Hong Park
Korea Astronomy and Space Science Institute (KASI)
The Occurrence and Speed of CMEs Related to Magnetic Helicity Injection in Their Source Regions
oral
Long-term (a few days) variation of magnetic helicity injection is calculated for 28 active regions which produce 46 CMEs to find its relationships with the CME occurrence and speed. It is found that the 46 CMEs are categorized into two different groups by two characteristic evolution patterns of helicity injection in their source active regions: (1) a monotonically increasing pattern with one sign of helicity (Group A; 30 CMEs in 23 active regions) and (2) a pattern of significant helicity injection followed by its sign reversal (Group B; 16 CMEs in 5 active regions). In addition, a fairly good correlation between the helicity injection rate and the CME speed is found for the 30 CME events in Group A, with a logarithmic correlation coefficient of 0.71. It is suspected that these two groups may have different preconditions and trigger mechanisms; CMEs in Group A seem to be associated with kink instability and CMEs in Group B seem to be involved with emergence of the helicity in the opposite sign into existing helicity system.
118
Susanta Kumar Bisoi
Senior Research Fellow, Physical Research Laboratory, Ahmedabad, India
Solar Polar Fields During Cycles 21-23: Correlation with Meridional Flows
oral
We have examined polar magnetic fields for the last three solar cycles, viz. Cycles 21, 22, and 23 using NSO/Kitt Peak synoptic magnetograms. In addition, we have used SOHO/MDI magnetograms to derive the polar fields during Cycle 23. Both Kitt Peak and MDI data at high latitudes (78° – 90°) in both solar hemispheres show a significant drop in the absolute value of polar fields from the late declining phase of the Solar Cycle 22 to the maximum of the Solar Cycle 23. We find that long-term changes in the absolute value of the polar field, in Cycle 23, are well correlated with changes in meridional-flow speeds that have been reported recently. We discuss the implication of this in influencing the extremely prolonged minimum experienced at the start of the current Cycle 24 and in forecasting the behavior of future solar cycles.
119
T.G. Priya
Indian Institute of Astrophysics, Kodaikanal
None
poster
None
120
Takashi Sakurai
National Astronomical Observatory of Japan
Conference Summary
invited
In addition to the summary of papers given in the meeting, I will describe the statistics showing the position of Asia-Pacific regions in solar physics.
121
V.VASANTH
Research Scholar, School of Physics, Madurai Kamaraj University.
The Characteristic investigations on Type-II bursts associated with Fast and Slow CMEs
poster
The investigations on the characteristics and relationships of meter and Deca-Hectometer wavelength ranges and associated with CMEs during the period 1997-2008 is presented. The sample of type-II burst pairs and associated CMEs are divided into two groups based on the CME speeds: Group I events, the type-II bursts associated with fast CMEs (speed > 900 km s-1); Group II, which are the type-II bursts associated with slow CMEs (speed < 900 km s-1). Our studies consist of three steps: i) the comparative studies on the characteristics of m-and DH-type-II bursts; ii) the delay time analysis of type-II bursts with flares and CMEs and iii) the characteristics study on flares and CMEs of Group I and Group II events. The main results will be presented in this paper.
122
Vema Reddy Panditi
Student
A multi-wavelenth study of filament eruption leading to a two ribbon M1.0 class flare/CME in NOAA AR 11093
oral
We present multi-wavelength analysis of a two ribbon M1.0 class flare that occurred in NOAA Active Region 11093 on August 7, 2010. This event was extensively observed by the recent space borne instrument onboard SDO in several wavelengths. Additional observational data was also obtained from STEREO,HESSI and the ground based NSO/GONG H-alpha network telescope. From these observations, we inferred an upward rising motion of inverse S-shaped filament lying along the polarity inversion line (PIL) originating from the main sunspot. This motion appears to have triggered the filament eruption subsequent to the reconnection. Associated signatures of the transient event were observed at the chromosphere as the flare ribbons and a fast moving CME in the outer corona. Brightening in H-alpha and changes in the topology of field lines, as traced from the images obtained in coronal lines, near the sunspot provide the evidence for flux emergence within and around the sunspot. We suggest that this flux emergence might have caused the flux rope to rise, resulting in the tethers to cut and reconnection to take place, in agreement with the tether cutting model. rnrn
123
VIDYA CHARAN DWIVEDI
Physics Department,A.P.S. University, Rewa (M.P.) 486 003, India
LONG-TERM STUDY OF SOLAR WIND PARAMETERS AND THEIR IMPACT ON GEOMAGNETIC FIELD ON 27 DAY AVERAGE BASIS
poster
In-situ measurements of solar wind and interplanetary magnetic field began in late 1962, which by now cover more than four solar cycles. Only, in the early stage, the data coverage was scanty with many days’ gaps. These in-situ observations, including the most commonly used solar activity index Rz(the sunspot number), have helped in establishing several useful statistical relationships between indices of geomagnetic activity and the interplanetary parameters. The product of V and B (VB) has recently been reported to be the most effective interplanetary parameter yielding the highest correlation with geomagnetic indices, even though earlier studies covering different intervals of time had either advocated for V, or for some other combinations. For the reported long-term correlative study, we have used the 27 day average values of the interplanetary indices (V, B, Bz, T, and N), as well as that of the geomagnetic disturbance index Ap, for the years 1965 to 2008. The averages have been calculated by choosing only those days for which simultaneous data is available for all these parameters (V, B, Bz, T, N and Ap). The statistical results so obtained for the whole period, can be summarized as: (1) that the sunspot number Rz is strongly correlated only with the IMF magnitude B (r = 0.65± 0.02), though the correlation is found to be low for the solar cycle 20(r = 0.38± 0.04). Even product VB is marginally associated with Rz. (2) that only solar wind speed V is strongly associated with its temperature, whereas marginal correlations are not observed amongst other interplanetary par
124
Vinod Krishan
Indian Institute of Astrophysics
none
invited
none
125
Virendra K. Verma
Uttarakhand Space Application Center, Dehradun-248006
On North-South Asymmetry of Solar Activity Phenomena
invited
The long-term behavior of North-South (N-S) asymmetryrnrelated to solar activity phenomena are investigated. In the investigation we have used sunspots data (1821-2011), flare indexrndata (1936-2009), soft-x-ray flares data (1976-2010) and solar active prominences (1957-2010) data for various solar cycles. Thernstatistical technique was used check the validity of asymmetry. Earlier Verma (1992, 1993, and 2009) reported long-term cyclicrnperiod 11 solar cycles in N-S asymmetry and also predicted that the N-S asymmetry of solar activity phenomena during solar cyclesrn21, 22, 23 and 24 will be south dominated and the N-S asymmetry will shift to north hemisphere in solar cycle 25. The present study shows that the N-S asymmetry during solar cycles 22 and 23rnwere southern dominated as predicted by Verma (1992). The initial years (2009-2011) of solar cycle 24th are showing southern domination and tend to confirm the result of Verma (1992). The 11rnsolar cycle’s periodic behavior of the Sun may be related to internal structure of the Sun. The result of this study may bernhelpful to understand long-term helioseismic phenomena and dynamornmodels of the Sun which are based on the magnetic fields related to solar active regions.rnrnReferences:rnrnVerma, V.K. (1992) ASP Conference Series, 27, 429.rnVerma, V. K. (1993) APJ, 403, 797.rnVerma, V.K. (2009) ASP Conference Series, 416, 483.rn
126
Wahab Uddin
Aryabhatta Research Institute of Observational Sciences (ARIES)
Magnetic Complexity and Flare from NOAA AR 10501 on 17 November, 2003
oral
We analyze the Hα (observed from ARIES, Nainital) and UV/EUV (TRACE) observations of 1N/M4.2 flare occurred in the active region NOAA 10501 on 17 November, 2003. The flare was initiated by the partial eruption of a huge ‘U’-shaped filament located in the south-west of the active region, and it was associated with a coronal mass ejection (CME). The flare showed two ribbons, in which one was of the reverse sigmoid shape and other was with a simple configuration. Based on the Hα observations, we detect the flare footpoints and compute the shear angle. We found that the shear angle decreases with the progress of flare. The active region has βγ configuration on 17 November, 2003. SOHO/MDI magnetogram shows that before the flare the negative polarity in the flare site breaks and started to move in southward direction. Using the magnetic field motion, we compute the magnetic helicity in the active region and discussed its role with the flare initiation. The flare and observed associated phenomena can be explained by the helical twisted flux rope model.rn
127
Y. P. Singh
Deptt. of Physics, Mangalayatan University, Aligarh
Study of short- and mid-term periodicities in solar data using wavelet analysis
poster
We have performed the wavelet analysis of daily and monthly average data of three solar indices namely sunspot number (SSN), 10.7 solar radio flux (SRF) and solar flare index (SFI). Four solar cycles’ data were used for SSN and SRF, and for SFI three cycles data were utilized. Results of the wavelet power spectrum analysis obtained using the monthly data of the SSN, SRF and SFI reveals that there are ~5.3, ~10.5, ~20.0 and ~36.0 year’s periodicities in SSN, ~2.4, ~10.7, and ~36.8 year’s periodicities in SRF and ~1.8, ~3.3 and ~10.4 years periodicities in SFI. The observed periodicities are highly intermittent in time. When daily solar indices were used for wavelet analysis, we observed two pronounced periodicities of ~27 days and ~155 days in all three solar indices.
128
Yang Guo
Department of Astronomy, Nanjing University
Driving Mechanism and Onset Condition of a Confined Eruption
oral
We find a magnetic flux rope before the M1.1 flare in active region 10767 on 2005 May 27 by a nonlinear force-free field (NLFFF) extrapolation. The flux rope coincides with the eastern part of the H_alpha filament, whose western part has a magnetic arcade structure. TRACE observations of the flux rope or filament eruption show a strong writhing motion of the erupting structure, suggesting that the flux rope converted some of its twist into writhe during the eruption. After calculating the twist of the pre-eruptive flux rope, we find that it is in very good agreement with thresholds of the helical kink instability found in numerical simulations. We conclude that the activation and rise of the flux rope were triggered and initially driven by the kink instability. We also estimate the height distribution of the decay index of the external magnetic field before the eruption with a potential field. The decay indices stay below the threshold for the torus instability for a significant height range above the erupting flux rope. This provides a possible explanation for the confinement of the eruption. The ultraviolet flare ribbon of the flare coincides well with the intersection between the quasi-separatrix layer (QSL) and the photosphere, while hard X-ray (HXR) sources at the peak of the M1.1 flare seem to coincide with the footpoints of the erupting helical structures, which indicates a high possibility that HXR sources are produced more efficiently in the flux rope.
129
Yeon-Han Kim
Solar & Space Weather Research Group, Korea Astronomy and Space Scienc
An examination of spicule oscillations observed by Hinode SOT
oral
Recent high-resolution observations by solar space missions (TRACE, SOHO, and Hinode) reveal that the solar atmosphere is full of many wave-like oscillations in various scales. In this study, we examined the oscillation signatures in the spicules observed by the Hinode SOT. On 2008 June 3, we identified a relatively long-lived oscillating spicule (oscillating period ~ 130 s, lifetime ~ 450 s) in the north polar limb of the Sun. For this event, we made space-time plots using time series images of the spicule and investigated the cross-correlation among them to estimate the phase difference of the oscillation with heights and its propagating speed. We found that the mean phase delay over the height difference of 3000 km is about 13 s. This result suggests that the oscillation is a propagating wave and the propagating speed is about 220 km s-1. Interestingly, this event also shows that the estimated wave speeds increased with height from 100 to 300 km s-1 over 5000 km height range. In addition, we examine more examples of spicule oscillations based on this kind of analysis. We will present the results and discuss the implication of oscillation signatures.
130
Yihua Yan
Key Laboratory of Solar Activity, National Astronomical Observatories,
On the Construction of Chinese Spectral Radioheliograph
invited
Imaging spectrocopy over cm-dm wave range is important for addressing fundamental processes in the solar eruptive phenomena. The Chinese Spectral Radioheliograph (CSRH) in 0.4-15 GHz range with high time, space and frequency resolutions is being constructed, which will open new observational windows on solar flares and CMEs. The CSRH array is located in a radio quiet region in Inner Mongolia of China. The array of CSRH in 0.4-2.0 GHz with 40 4.5m antennas has been mounted by the end of 2010. The array of CSRH in 2-15 GHz with 60 2m antennas will be established by 2013. The progress about the CSRH project is introduced.
131
Yuhong Fan
National Center for Atmospheric Research
Dynamics of Active Region Flux Tubes in the Solar Convection Zone
invited
Active regions on the solar surface are generally thought to originate from a strong toroidal magnetic field generated at the base of the solar convection zone by a deep-seated solar dynamo. Understanding the dynamic rise of active region flux from the base of the convection zone to the surface is therefore a crucial component for the study of the solar cycle dynamo. In this talk I will give an overview of recent new results on the rise of active region flux tubes in the solar convective envelope from both a thin flux tube model incorporating the effects of giant cell convection as well as direct 3D spherical-shell anelastic MHD simulations. It is found that the dynamic evolution of the flux tube changes from magnetic buoyancy dominated to convection dominated as the initial field strength of the flux tube varies from about 100 kG to 15 kG. I will discuss the implications of these results with regard to the field strength of the dynamo generated large-scale toroidal magnetic field at the base of the solar convection zone.
132
Zhong Liu
Chinese Academy of Sciences
1-meter near infrared solar tower
invited
In order to observe the fine structure of solar dynamical field and magnetic field, a 1-meter near infrared solar telescope was built by Chinese Academy of Sciences. The telescope and tower locate on the side of Fuxian Lake, Yunnan, China. The details of this telescope such as science cases, structure, instruments and the parameters of site are introduced in this talk. The first light of high resolution photosphere images and movies are also introduced too.
