भारतीय खगोलभौतिकी संस्थान
Indian Institute of Astrophysics
Exploring the Universe since 1786
An Autonomous Institute under the
Department of Science & Technology
Government of India
Research Highlights
RESEARCH HIGHLIGHTS | IIA
Low-resolution transit spectroscopy of three hot Jupiters using the 2 m Himalayan Chandra telescope
SIVARANI, T | Nov 01, 2024
Here, we present the low-resolution transmission spectroscopy of three giant planets using the Himalayan Faint Object Spectrograph Camera (HFOSC) on the 2 m Himalayan Chandra Telescope (HCT) in Hanle, India. It is the first application of transmission spectroscopy with HCT. This study presents results from a single transit, each for three planets: HAT-P-1b, KELT-18b, and WASP-127b. The selection of suitable reference stars assisted in accurately tracking slit losses for the long cadence observations that are needed to achieve the required signal-to-noise ratio (SNR). We employ the common mode correction technique, utilizing a white light transit curve to minimize time-dependent systematic errors. The observed spectra for WASP-127b and HAT-P-1b agree with previouslow-resolution transitspectroscopic observations using other observing facilities. We confirm the presence of Rayleigh scattering in the atmosphere of WASP-127b. In addition, we provide the first low-resolution transmission spectrum for KELT-18b. Modelling the exoplanet atmosphere with HFOSC and available IR observations from HST and Spitzer for WASP-127b and HAT-P-1b shows that HFOSC can be an alternative optical instrument to use in conjunction with IR observations to constrain the atmospheric parameters better
RESEARCH HIGHLIGHTS | IIA
A compilation of optical starlight polarization catalogs
ARCHANA SOAM | Jan 01, 2025
Polarimetry of stars at optical and near-infrared wavelengths is an invaluable tool for tracing interstellar dust and magnetic fields. Recent studies have demonstrated the power of combining stellar polarimetry with distances from the Gaia mission, in order to gain accurate, 3D information on the properties of the interstellar magnetic field and the dust distribution. However, access to optical polarization data is limited, as observations are conducted by different investigators, with different instruments, and are made available in many separate publications. To enable a more widespread accessibility of optical polarimetry for studies of the interstellar medium, we compile a new catalog of stellar polarization measurements. The data are gathered from 81 separate publications spanning two decades since the previous, widely used agglomeration of catalogs by C. Heiles. The compilation contains a total of 55,742 measurements of stellar polarization. We combine this database with stellar distances based on the Gaia Early Data Release 3, thereby providing polarization and distance data for 42,482 unique stars. We provide two separate data products: an extended catalog (containing all polarization measurements) and a unique source catalog (containing a subset of sources excluding duplicate measurements). We propose the use of a common tabular format for the publication of stellar polarization catalogs to facilitate accessibility and increase discoverability in the future
RESEARCH HIGHLIGHTS | IIA
Challenges in modeling the dark matter halo of NGC 1052–DF2: Cored versus cuspy halo models
ADITYA, K | Sep 01, 2024
The discovery of NGC 1052−DF2 and subsequent modeling have shown that NGC 1052−DF2 is deficient in dark matter and is in conflict with the standard stellar-to-halo mass ratio. In this work, we aim to resolve the degeneracy between the dynamical models on the mass estimate of the NGC 1052−DF2. Methods. We constructed mass models of NGC 1052−DF2 using an anisotropic distribution function with a radially varying anisotropy parameter and studied the effect of the various model parameters on the dark matter estimates. We used the observed stellar photometry as an input parameter to construct the distribution function and employed a Markov chain Monte Carlo (MCMC) method to estimate the dark matter model parameters. Results. We find that mass models with a cuspy dark matter halo have comparable χ2 to models with zero dark matter. Moreover, the cuspy dark matter halo fails to consistently account for the observed velocity dispersion in the inner and outer regions of the galaxy. Consequently, we rule out the possibility of a cuspy dark matter halo for describing the mass models of NGC 1052−DF2. Our study shows that the cored dark matter halo model with a total mass of log(MDM/M⊙) = 10.5 explains the observed kinematics but requires an extraordinarily large scale length (20 kpc) and an outer cutoff radius (26 kpc). While the cored mass model provides a comparatively better fit, our findings emphasize that the mass models are largely unconstrained by the available kinematic data. Our results suggest that NGC 1052−DF2 may not only have an ultra-diffuse stellar distribution but that it can, within uncertainties in the available kinematic data, potentially host an ultra-diffuse dark matter distribution compatible with the standard stellar-to-halo mass relation (SHMR) predicted by galaxy formation and evolution models
Press Releases
PRESS RELEASES | SCOPE
Hanle Dark Sky Reserve star party brings together astronomy enthusiasts for the third year
SCOPE | Sep 26, 2025
Astronomy enthusiasts from across the country participated in amateur astronomy and astrophotography related activities at the third edition of the HDSR Star Party that was jointly organised by the Indian Institute of Astrophysics (IIA), Department of Wildlife Protection of UT Ladakh, and Bhabha Atomic Research Centre (BARC) between 18 and 23 September.
The PIB press release is here.
The DST press release is here.
PRESS RELEASES | SCOPE
Black holes and cosmic jets join forces to shape galaxies
SCOPE | Oct 21, 2025
Black hole activities suppress the birth of new stars around it, shows a new study that can help in a deeper understanding of how galaxies evolve and may provide answers to why some have very low star-formation rates.
This study was published in the Astrophysical Journal, titled “Warm Ionized Gas Outflows in Active Galactic Nuclei: What Causes Them?”, and is authored by Payel Nandi and C.S. Stalin from IIA and D.J. Saikia from IUCAA.
The PIB press release is here.
The DST press release is here.
The paper can be downloaded from here.
PRESS RELEASES | SCOPE
Astronomers unearth unexpected chemical link during stellar evolution
SCOPE | Nov 14, 2025
A new study has traced a link between Lithium-rich red giant stars and their enhanced Helium abundance, using data from the Himalayan Chandra Telescope and other archival data. The study gives a new lead to the evolution of cool giant stars along the red giant phase.
This study was published in The Astrophysics Journal as a paper titled "Photospheric Helium Abundance in Cool Giants: A Comprehensive Study", by B. P. Hema and Gajendra Pandey of IIA.
The PIB press release is here.
The DST press release is here.
The paper can be accessed here.
Study at IIA
PhD Programme
IIA offers a vigorous programme of graduate studies that forms a vital component of research & training. The programme is overseen by the board of graduate studies. The Institute is also a major partner in the Joint Astronomy Programme (JAP), organized by the Indian Institute of Science.
Admissions
PhD applications may be submitted through the IIA PhD online applications portal in May. After the initial screening, shortlisted candidates will be interviewed in June. The final list of selected candidates will be announced in July, followed by the commencement of the programme in August. .
Research Fields
Solar Studies
Studies of the Sun and solar system have been the longest pursued discipline at IIA. Members of the group conduct theoretical, numerical modeling, and observational studies in solar physics.
Stars & Galaxies
Research interests of the group members range from exoplanets, star formation, stellar evolution, end states of stars, Interstellar medium, the milky way Galaxy, nearby galaxies, active galaxies and time domain astronomy.
Theory
Members of the theoretical Astrophysics group work on a broad range of topics such as black hole astrophysics, pulsars, exoplanets, astrophysical turbulence & magnetic fields, MHD, cosmology and early universe.
Notice Board
Tenders, Technically Qualified Vendors & e-Auction Notices | GSTIN: 29AABTI0567R1ZZ
Job Opportunities
Galleries
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
150 YEARS OF VANDE MATARAM | 2025
150 years of 'Vande Mataram'
VIGILANCE PLEDGE | 2025
Vigilance pledge
VIGILANCE PLEDGE | 2025
