IIA ARCHANA SOAMKinematic study of molecular gas in cometary globule – LBN 437
Bright-rimmed, cometary-shaped star-forming globules, associated with H II regions, are remnants of compressed molecular shells exposed to ultraviolet radiation from central OB-type stars. The interplay between dense molecular gas and ionizing radiation, analysed through gas kinematics, provides significant insights into the nature and dynamic evolution of these globules. This study presents the results of a kinematic analysis of the cometary globule, Lynds’ Bright Nebula (LBN) 437, focusing on the first rotational transition of 12CO and C18O molecular lines observed using the Taeduk Radio Astronomy Observatory. The averaged 12CO spectrum shows a slightly skewed profile, suggesting the possibility of a contracting cloud. The molecular gas kinematics reveals signatures of infalling gas in the cometary head of LBN 437, indicating the initial stages of star formation. The mean infall velocity and mass infall rate towards the cometary head of LBN 437 are 0.25 km s−1 and 5.08 × 10−4 M yr−1, respectively, which align well with the previous studies on intermediate or high-mass star formation.
IIA WAGEESH MISHRAProton heating estimates from near-Earth observations of coronal mass ejections in solar cycle 24 Open Access
As solar coronal mass ejections (CMEs) propagate through the heliosphere, they expend energy in heating protons to compensate for the cooling that occurs due to expansion. CME propagation models usually treat energy dissipation implicitly via a polytropic index (δ). Here we calculate the power dissipation implied by a given δ and compare it with the power available in the turbulent velocity fluctuations. We make this comparison using near-Earth in-situ observations of 27 of the most geoeffective CMEs (Dst < −75 nT) in solar cycle 24. For δ = 5/3, the power in the turbulent velocity fluctuations is ≈54% smaller than what would be required to maintain the proton temperature at the observed values. If the power in the turbulent cascade is assumed to be fully expended in local proton heating, the most probable value for δ is 1.35. Our results contribute to a better understanding of CME energetics, and thereby to improved CME propagation models and estimates of Earth arrival times.
IIA SIVARAM, CIs asteroid 33 Polyhymnia a dark matter (DM) degenerate object?
Polyhymnia (33 Polyhymnia) is a main belt asteroid in our solar system with a diameter around 54 km. The density of asteroid 33 Polyhymnia, located in the main asteroid belt, is calculated to be 75 g/cc. Researchers have speculated the possibility that Polyhymnia could be composed of high-density superheavy elements near atomic number 164. Here, we propose that Polyhymnia could be an asteroid composed of degenerate dark matter (DM) and there could be many such asteroids in our solar system. (This is following our earlier work suggesting that Planet Nine could be such an object.)
IIA SRIRAM, SOptical design studies for national large optical-IR telescope
A 10–12 m class national large optical-IR telescope (NLOT) is envisaged to meet the growing scientific requirements in astronomy and astrophysics. Telescopes of such dimensions can only be made by segmenting the primary mirror, as it eases a more prominent primary mirror’s fabrication, transportation, operation, and maintenance process. This paper presents the various optical designs analyzed for NLOT that can be fabricated using the India TMT Optics Fabrication Facility (ITOFF) at the Centre for Research and Education in Science and Technology (CREST) campus. We present the primary mirror segmentation details, its ideal optical performance, and study each design’s advantages and technical complexities. Based on the above analysis, we have narrowed it down to an optimal design, and its performance analysis is also discussed.
IIA JAYANT JOSHIQuiet Sun Ellerman bombs as a possible proxy for reconnection-driven spicules
Context. Spicules are elongated, jet-like structures that populate the solar chromosphere and are rooted in the lower solar atmosphere. In recent years, high-resolution observations and advanced numerical simulations have provided insights into their properties, structures, and dynamics. However, the formation mechanism of spicules, particularly the more dynamic type II spicules, which are primarily found in the quiet Sun and coronal holes, remains elusive. Aims. This study explores whether quiet Sun Ellerman bombs (QSEBs), which are ubiquitous small-scale magnetic reconnection events in the lower atmosphere, are linked to the formation of type II spicules. Methods. We analysed a high-quality 40-minute time sequence acquired with the Swedish 1-m Solar Telescope. Hβ data were used to observe QSEBs and spicules, while spectropolarimetric measurements in the photospheric Fe I 6173 Å line provided line-of-sight magnetic field information. We employed k-means clustering to automatically detect QSEBs and explored their potential association with spicules. Results. We identified 80 clear cases in which spicules occurred soon after the QSEB onset and not later than 30 s after the ending of the QSEBs. In all these instances, the events involved type II spicules, rapidly fading from the images. The footpoints of the spicules seemed to be rooted in QSEBs, where the onset of QSEBs often preceded the formation of the associated spicules. In addition to these clear cases, we found around 500 other events that hinted at a connection but with some ambiguities. The combined clear and ambiguous cases constitute 34% of the total detected QSEBs and a smaller percentage of the spicules in our dataset. Conclusions. Our findings suggest that a fraction of the type II spicules originate from QSEBs, supporting magnetic reconnection as a potential driving mechanism. In this context, QSEBs and spicules represent the conversion of magnetic energy into thermal and kinetic energy, respectively. We suggest that an observational programme including multiple Balmer lines would likely detect more unambiguous connections between QSEBs and spicules.
IIA PRAVABATI CHINGANGBAMGlobal 21 cm signal: a promising probe of primordial features
Inflationary models that involve bursts of particle production generate bump-like features in the primordial power spectrum of density perturbations. These features influence the evolution of density fluctuations, leaving their unique signatures in cosmological observations. A detailed investigation of such signatures would help constrain physical processes during inflation. With this motivation, the goal of this paper is two-fold. First, we conduct a detailed analysis of the effects of bump-like primordial features on the sky-averaged 21 cm signal. Using semi-numerical simulations, we demonstrate that the primordial features can significantly alter the ionization history and the global 21 cm profile, making them a promising probe of inflationary models. We found a special scale (namely, the turnover wavenumber, kturn) at which the effect of primordial bump-like features on the global 21 cm profile vanishes. Also, we found that the behaviour of the primordial features on the global profile and ionization history are quite opposite for k > kturn and k < kturn. We trace the root cause of these behaviours to the effects of primordial features on the halo mass function at high redshifts. Furthermore, we discuss the degeneracy between the astrophysical parameters and the primordial features in detail. Secondly, for a fixed set of astrophysical parameters, we derive upper limits on the amplitude of bump-like features in the range 10-1 < k [ Mpc^-1] < 102 using current limits on optical depth to reionization from CMB data by Planck.
IIA NAGARAJU, KTest and Calibration of the Solar Ultraviolet Imaging Telescope (SUIT) on Board Aditya-L1
The Solar Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1 mission observes the Sun in the 200 – 400 nm wavelength range. This paper presents the results of various on ground and on-board tests and their comparison with the specifications. Moreover, we also present the scheme for data calibration. We demonstrate that the test results are compliant with the specified numbers, except the spatial resolution. Such discrepancy will limit the photometric measurements only, at a scale of 2.2 instead of 1.4 as originally envisioned.The results obtained here show that SUIT observations open a new window for solar observations.
IIA JAYANT MURTHYUltraviolet Background Radiation from Not-So-Dark Matter in the Galactic Halo
Murthy et al. (2025) (hereafter Paper I) have recently reported the discovery of unexpectedly bright diffuse extreme-ultraviolet radiation at high latitudes in both the Northern and Southern Galactic Hemispheres. After correction for extinction by the total interstellar dust in the direction of each observation, the spectra are nearly identical, suggesting that the radiation has a unique source and likely originates in the halo of our galaxy. The observed spectrum extends down to 912 Å, the interstellar hydrogen absorption edge. Radiation even slightly short of that edge would, if ubiquitous, be sufficient to explain the high degree of ionization in our galaxy and throughout the universe. We hypothesize that this newly discovered radiation originates in the slow decay of dark matter. The intensity of the radiation implies that the decay cannot be via the weak interaction, suggesting the existence of a new, even weaker fundamental interaction, consistent with the exceedingly long decay lifetime required.
IIA ARUNA GOSWAMIHigh-resolution spectral analysis of three high-latitude carbon stars
We present the results of a detailed high-resolution spectroscopic analysis (SUBARU/HDS spectra, R ∼50,000) of three faint high-latitude carbon stars HE 1104 − 0957, HE 1205 − 0521, and HE 1244 − 3036. Our estimated metallicity for these objects is − 2.96, − 2.63, and − 2.49, respectively. The surface chemical compositions of the objects are found to be characterised by enhanced carbon and heavy elements, such as Y, Ba, La, and Ce. Using the classification criteria for carbon-enhanced metal-poor (CEMP) stars the objects HE 1104 − 0957 and HE 1205 − 0521 could not be classified into any known CEMP sub-classes, whereas the object HE 1244 − 3036 is found to be likely a CEMP-s star. The observed abundance patterns in HE 1244 − 3036 are also found to match well with the yields of a 2 M ⊙ AGB star with [Fe/H] = − 2.50. Although our kinematic analysis indicates that the objects belong to the halo population, the elemental abundance ratios of HE 1104 − 0957 and HE 1205 − 0521 do not match well with those of typical halo objects. Estimated elemental abundances are presented, and kinematic properties of the stars are discussed.
IIA BHARAT P. CHANDRALow-cost Raspberry Pi star sensor for small satellites. II: StarberrySense flight and in-orbit performance
Star sensors are an essential instrument used to determine the attitude of satellites by identifying the stars in the field of view. The high cost and large sizes of commercially available star sensors pose challenges for small satellite missions. We at the Indian Institute of Astrophysics have developed a low-cost star sensor, StarberrySense, based on the Raspberry Pi as the main controller and built from commercial off-the-shelf components. The StarberrySense was flown on the PS4 experimental orbital platform module of the Polar Satellite Launch Vehicle C-55 by the Indian Space Research Organization. This work describes the flight hardware, environmental tests in preparation for the flight, and in-orbit performance of our StarberrySense.