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
Multiwavelength Observations of Multiple Eruptions of the Recurrent Nova M31N 2008-12a
JUDHAJEET BASU | May 01, 2024
We report the optical, UV, and soft X-ray observations of the 2017–2022 eruptions of the recurrent nova M31N 2008-12a. We find a cusp feature in the - and -band light curves close to the peak, which could be related to jets. The geometry of the nova ejecta based on morpho-kinematic modeling of the Hα emission line indicates an extended jet-like bipolar structure. Spectral modeling indicates an ejecta mass of 10−7–10−8M⊙ during each eruption and an enhanced helium abundance. The supersoft source phase shows significant variability, which is anticorrelated to the UV emission, indicating a common origin. The variability could be due to the reformation of the accretion disk. We infer a steady decrease in the accretion rate over the years based on the intereruption recurrence period. A comparison of the accretion rate with different models on the plane yields the mass of a CO white dwarf, powering the H-shell flashes every ∼1 yr, to be >1.36 M⊙ and growing with time, making M31N 2008-12a a strong candidate for the single degenerate scenario of the Type Ia supernovae progenitor.
RESEARCH HIGHLIGHTS | IIA
GC 7314: X-ray study of the evolving accretion properties
ARUN MANGALAM | Nov 20, 2024
We present a comprehensive analysis of the timing and spectral properties of NGC 7314, a Seyfert 1.9 galaxy, using X-ray observations from XMM-Newton, NuSTAR, and RXTE/proportional counter array (PCA). The timing analysis reveals significant variability across different energy bands, with fractional variability values consistent with previous studies. The highly variable soft photons and comparatively less variable high-energy photons imply different origins of these two types. The soft energy photons come from a hot corona near the center, while the high-energy photons are produced by inverse Compton scattering of these primary X-ray photons in a hot plasma away from the central region. The spectral analysis employs various models to characterize the emission components. The results indicate the presence of a soft energy bump, Fe Kα line emission, and a prominent reflection component. The long-term RXTE/PCA data analysis reveals temporal variations in the photon index (Γ) and power-law flux, suggesting evolving emission properties over time. The signature of both broad and narrow Fe Kα emission line features suggested the broad, variable one coming from the accretion disk (∼10‑5 pc), while the nonevolving narrow line cannot be well constrained. The absorption feature could originate in a highly ionized region, possibly closer to the broad-line region. The evolution of the inner accretion properties indicates that NGC 7314 could be a potential changing-state active galactic nucleus.
Press Releases
PRESS RELEASES | SCOPE
Indian Institute of Astrophysics Training Workshop at Kodaikanal and Kavalur for Total Lunar Eclipse
SCOPE | Aug 05, 2025
A total lunar eclipse is to occur on the night of 7-8 September 2025, which will be visible from all over India. IIA therefore organised two “Train the Trainers” Workshops during 2-3 August 2025, one at the Vainu Bappu Observatory in Kavalur, and the other at the Kodaikanal Solar Observatory in Kodaikanal. These workshops were to train science and astronomy communicators and teachers in Tamil Nadu and Puducherry so that they can in turn organise preparatory workshops and eclipse viewing camps in their neighbourhoods.
Link to PIB article here.
PRESS RELEASES | SCOPE
A new window into the stars by modeling stellar atmosphere
SCOPE | Aug 22, 2025
In a major advance in computational astrophysics, IIA astronomers and collaborators have developed a method to compute more realistic properties of stellar atmospheres. The method opens the door to more realistic simulations of stellar spectra — the primary tool astronomers use to decode the physical conditions in stars, circumstellar disks, and interstellar clouds.
This is based on the paper titled "Full non-LTE multi-level radiative transfer: I. An atom with three bound infinitely sharp levels", by Lagache T., Paletou, F., and Sampoorna, M., Astronomy and Astrophysics, 2025, 699, A198.
Press release by DST published here.
Press release by PIB published here.
Download the paper here.
PRESS RELEASES | SCOPE
Astronomers unveil observational evidence of how cosmic dust grains line up with the Galaxy’s magnetic field
SCOPE | Sep 03, 2025
Scientists have long believed that just like dust particles dancing in a ray of light, tiny cosmic particles floating between stars in the Milky Way act as storytellers of the universe. Now a team of astronomers, has just uncovered the strongest observational evidence yet of how these interstellar dust grains align themselves with magnetic fields in our Galaxy.
This is based on the paper titled "B-fields and Dust in Interstellar Filaments Using Dust Polarization (BALLAD-POL). III. Grain Alignment and Disruption Mechanisms in G34.43+0.24 Using Polarization Observations from JCMT/POL-2", by Saikhom Pravash, Archana Soam, Pham Ngoc Diep, Thiem Hoang, Nguyen Bich Ngoc, and Le Ngoc Tram, The Astrophysical Journal, 2025, 981, 128.
Press release by DST published here.
Press release by PIB published here.
Download the paper here.
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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.
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