It is with immense pleasure that I summarise the activities of the Institute over the past year, which once again have been a rich mix of highly productive scientific research, developmental efforts and teaching in multiple programmes, in addition to conferences and other events on a wide range of topics for both the specialist and the public.
A highlight of Solar physics activity was observations of a total solar eclipse for the second year in succession, this time observed from the Polynesian island of Rapa Nui, or Easter Island in the Pacific. On the computational side, three new efficient numerical methods were developed to solve the polarized line transfer equation with angle-dependent PRD function, and the classical theory of PRD was generalised for atomic transitions with arbitrary quantum numbers. From an analysis of the linearly polarised (Second) limb solar spectrum, it was demonstrated that weak vector magnetic fields in the solar chromosphere can be investigated by combining the forward scattering Hanle effect near the disk centre with the longitudinal Zeeman effect. Using a new technique to solve the three-dimensional radiative transfer equation, the scattering matrix for quantum interference in the presence of arbitrarily strong magnetic fields has been derived.

High-cadence spectropolarimetry of sunspots has shown that the helioseismically measured travel times receive direction dependent contributions from acoustic waves, and found evidence for acoustic wave sources beneath the umbral photosphere. An analysis of the travel times along the wave path in an active region suggests that structural perturbations are largely confined to the near-surface layers. From an analysis of digitized photoheliograms from the
Kodaikanal Observatory it was found that the dynamic behaviour of the sunspot penumbral area relative to its umbral area depends on the ambient magnetic field configuration and on the structure of the sunspot itself. From identification of rotational lines of the AlH molecule in sunspot umbral spectra, the rotational temperature was estimated to be approximately 3800 K. Doppler imaging of the sites of network regions near the disc centre of the quiet Sun showed that the nature of the interaction of acoustic waves with the small-scale magnetic fields of the quiet sun was similar to that of large scale magnetic fields in the active regions. Results from an analysis of quasi-periodic intensity variations of polar plumes using SoHO (Solar and Heliospheric Observatory) imaging are suggestive of the variations being magneto-acoustic waves rather than quasi-periodic high speed upflows. General solutions of non-linear force-free magnetic fields assuming spherical geometry were applied to vector-magnetograms of active regions obtained from Hinode, and the variation in energy and relative helicity for the active region as a function of time was derived. Fabry-Perot interferometric determination of the profiles of the coronal green line show secondary components at velocities between 20–40 km/s, suggesting that they are due either to type II spicules or the nascent solar wind flow. An analysis of extreme ultra-violet emission lines from the solar network region has shown that the intensities, Doppler velocities and line widths are enhanced in the network region. Detailed theoretical investigations were carried out using three dimensional magneto-hydrodynamic simulations to study the dynamics of magnetic fields in the network. In order to determine the dependence of radiative losses on the properties of the fluid, a model for solar granules has been developed. From analysis of sunspot group activity over a century, it is suggested that the decay of spot groups may enhance the energy output, and therefore contribute to the correlation between total solar radiance and sunspot activity. Analysis of the chromospheric velocity structures using spectropolarimetric data shows possible signatures of interaction between the plage magnetic fields and the overlying fields. A study of SoHO ultraviolet images suggests that coronal holes probably originate below the base of the convection zone and that they rotate rigidly. Weak low radio frequency bursts with intermediate brightness temperature were found to have no accompanying activity in H-alpha and X-rays, and the total energy of their non-thermal electrons was found to be much weaker than the corresponding values for hard X-ray microflares. Using the diffraction pattern created by the moon’s limb passing across the solar disc during a solar eclipse, the smallest sized discrete radio source in the corona known to date was discovered.

In the area of stellar physics, intra-day variability of the H-alpha profiles of pre-main sequence stars was seen, and the results were found to be most consistent with dynamic magnetospheric accretion and a disc wind. Differential multi-epoch photometry of the globular cluster NGC 6981 has yielded several new variables and enabled estimation of the physical parameters of the cluster. The triggered star formation scenario has been investigated using numerical simulations and the clump mass spectrum has been derived. A new Hydrogen-deficient carbon star has been discovered by IIA’s Himalayan Chandra Telescope. Oxygen abundances from near-infrared spectra of Carbon enhanced metal-poor stars from the Keck telescope suggest that the oxygen-enhancement could be due to a massive stellar wind or hypernovae pollution. 15 new Lithium-rich giant stars have been discovered using a spectroscopic survey with the VBO telescopes and HCT. V-band polarimetry of carbon-enhanced metal-poor stars suggest that the observed polarisation is due to circum-stellar grain scattering. Lithium abundances of stars in the alpha Persei cluster from high spectral resolution measurements suggest that the star-to-star spread in the abundance develops after about 20 Myr. Photometry and spectroscopy of the recurrent Nova U Scorpii suggest matter ejection at velocities of 10,000 km/s and rapid variation on time-scales of an hour. An investigation of the supernova SN 2009jf showed evidence for an explosion with large kinetic energy. A relativistic pulsar emission model that accounts for aberration and retardation was found to explain the the observed range of circular polarisation and position angle swing. Ultraviolet halos have been found for the first time around the stars Spica and Achernar, due to starlight scattered by thin dust clouds near the star. A long-term multi-epoch campaign with VBT and HCT to search for intermediatemass
black holes at the centres of globular clusters via their microlensing events has begun, and has resulted in ia the by-product discovery of several variable stars in the cluster NGC 5024.

In the area of extragalactic astrophysics, the structure of the Large Magellanic Cloud was investigated using its red clump stars, which imply structural warps in the LMC and suggest tidal effects. Multifrequency observations of blue compact dwarf galaxies have shown evidence for recently triggered star formation, stochastic self-propagating star formation and highly extended HI discs. Spectroscopy of low surface brightness galaxies have yielded central black hole masses that are in the intermediate black hole mass range. The well-known blazar Mkn 421 was detected by the HAGAR telescope in a flare state. Metallicities of the Bootes I dwarf spheroidal galaxy imply that such systems could have been contributors to the Galactic halo. Spectral fits to the the X-ray emission and radio imaging of active galaxies of the Seyfert type that were carefully selected to be intrinsically similar but spanning large range of orientations, yielded systematics of X-ray and radio luminosities, line-of-sight absorption and emission line strengths that indicate axisymmetric obscuring material in their nuclei. Quasars with broad absorption troughs in their ultraviolet spectra were found to have systematically lower X-ray luminosities than ordinary quasars. The mass of the central black hole in a Seyfert galaxy was derived by applying the reverberation mapping technique to multi-epoch data from HCT. A lower limit on the mass of the central black hole has been derived by modeling the variability
of the active nucleus. The energy index of relativistic electrons in distant galaxies can be accounted for redshifted synchrotron losses and do not need Fermi acceleration processes.

In the area of atomic and molecular physics, a relativistic coupled-cluster calculation was performed for the first time using three and four particle excitations which, when applied to the Al+ atomic clock, reduces systematic errors by 28%. Investigation of the quantum phases of ultracold bosonic atoms using the density matrix renormalization group have shown that the Mott insulator co-exists with the superfluid phase at an incommensurate density. A new limit for the electron dipolemoment (EDM) has been derived by combining the measured EDM of thallium with the ratio of atomic to electron dipole moments that was derived by applying the relativistic coupled-cluster theory to atomic thallium. The ionization potential, excitation energies and oscillator strengths of the Indium atom that were computed using the valence universal coupled cluster method were found to be in excellent agreement with experimental data. The hyperfine structure constants for the BaF molecule were calculated by applying the many-body perturbation theory via the Z-vector technique and were found to be good agreement with experimental determinations.

In the area of optical sciences, the cross talk induced by atmospheric seeing between the measured Stokes parameters of the solar emission line profiles, which impacts the derivation of the surface magnetic fields of the sun, was studied using the Lites formalism. Numerical simulations suggest that the prediction of wave front arrival by pixel-wise prediction of phase screens and slope extrapolation techniques are equally effective, while modal prediction can yield improved results. In order to increase the fidelity of images from high-resolution CCD cameras using microelectromechanical systems, experiments in noise reduction were conducted and it was found that using intensity-weighted noise removal significantly improved the image quality. The extendedmatched filter method was shown to enable the detection of periodic structures hidden in rough surfaces, which conventional methods bound by the usual Rayleigh criterion would fail to reveal. It has been demonstrated theoretically and experimentally that the dual-energy computed tomography inversion algorithms must use the full Klein-Nishina formula for the Compton scattering and the correct exponents for the photoelectric effect.

On the developmental front, the infrastructure for the installation of the 1.3 m telescope at the Vainu Bappu Observatory in 2012 is in full swing, as is the site-characterisation effort for the proposed 2 m class National Large Solar Telescope (NLST) in the Himalayas. NLST will be a unique state-of-the-art telescope for carrying out high-resolution studies of the Sun. A comprehensive design study has been carried out and a Detailed Project Report has been produced. A major activity in the MGK Menon laboratory at IIA’s Hosakote campus has been the assembly
and testing of the Ultra-violet Imaging Telescope (UVIT) payload to be launched on the ASTROSAT space astronomy mission next year. In addition, work commenced on various new programmes that include the development of a high-resolution Echelle spectrograph for the HCT, a 20 cm space coronograph on Aditya I and India’s participation in the mega-international Thirty-Metre Telescope project.

IIA’s new teaching programmes have continued, with the first batch of students from both the M.Sc.- Ph.D. and M.Tech.-Ph.D. programmes completing their Masters degrees (M.Sc. and M.Tech. respectively). IIA also hosted four students from the United States, who did research projects in IIA under the International Research Experience Programme funded by the National Science Foundation, USA.

IIA’s outreach activities reached new heights this year by building upon the collaborations established during the International Year of Astronomy in 2009. IIA played a major role in an inter-institutional astronomy festival christened Kalpaneya Yatre, a first-of-its-kind event in Bangalore wherein IIA scientists were involved in the design of the exhibition, and also led the activities component of the festival. Both young and adult audiences were targeted by these activities, and amateur astronomers, science popularisers, artist-designers and theatre artistes were all brought together to lead different events, which included Ask an Astronomer sessions, astronomy workshops for teachers and for children, art and theatre activities, sky-watching events, besides lectures on various topics. These activities reached thousands of people, and ended with an inter-disciplinary one-day symposium on Astronomy & Society: Public Ownership of Science.

IIA organised several meetings during the year, including international ones. The 3rd IIA-PennState Astrostatistics school continued to be a big draw as in the previous schools, with participation by astrophysicists of all levels including PhD students and faculty, and including several participants from Europe and other countries. The 3rd Indo-China workshop on Solar Physics along with the first Asia- Pacific Solar Physics meeting served as an excellent
platform to kick start several international collaborations. IIA hosted a Humboldt Kolleg on Self-organized Criticality: The Dynamics of Complex Systems, an inter-disciplinary conference supported by the Alexander von Humboldt Foundation, Germany. A highlight of the year was a conference to celebrate Chandrasekhar’s birth centenary. The focus was on research areas in which Chandrasekhar made seminal contributions during his lifetime, and included several review talks by stalwarts in those areas.

IIA hosted a wholesome blend of public lectures over the year that were extremely well received. India’s leading sociologist and writer Andre B´eteille gave the Bicentennial Commemorative lecture on Can Rights Undermine Trust? How Institutions Work and Why they Fail. IIA’s Founder’s Day which is celebrated on the birth anniversary of Vainu Bappu, had India’s renowned biochemist, G. Padmanaban, deliver a lecture on Growth of Biotechnology
in India. The fourth Vainu BappuMemorial lecture with the title What Makes Spiral Galaxies Tick? was delivered by renowned astrophysicist James Binney from the University of Oxford. The International Womens’ Day which this year occurred during the International Year of Chemistry, was celebrated with a public lecture and discussion on Dorothy Hodgkin, and this event served as a trigger for regular informal discussions through the year on a rich variety of topics, especially by students. IIA’s efforts on the implementation of the Hindi language have gathered considerable momentum this year. The IIA newsletter has been carrying pieces written in Hindi. In addition to language workshops, there was enthusiastic participation by the staff in a variety of language-based cultural activities. The

Institute continues to be proactive in building an equitable workplace by safeguarding the interests of SCs and STs as well as women. We are very proud of our Ph.D. student K. Sowmya who emerged as the top-ranker of Bangalore University in 2010 in the MSc Physics course and was awarded six gold medals for her performance, our Ph.D. student Avijeet Prasad, who emerged third in the National Level CSIR-NET examination, and our documentation specialist Sandra Rajiva, who was facilitated at the meeting of the Astronomical Society of India for her 25 years of service to the Bulletin of the ASI.