Search Publications
Dancing with the Stars: a Review on Stellar Multiplicity
Merle, Thibault
Stars like company. They are mostly formed in clusters and their lives are often altered by the presence of one or more companions. Interaction processes between components may lead to complex outcomes like Algols, blue stragglers, chemically altered stars, type Ia supernovae, as well as progenitors of gravitational wave sources, to cite a few. Ob…
Astrometric and Photometric Calibrators for the 4-m International Liquid Mirror Telescope
Kumar, Brajesh; Surdej, Jean; Negi, Vibhore +11 more
The International Liquid Mirror Telescope (ILMT) is a 4-meter class survey telescope. It achieved its first light on 29th April 2022 and is now undergoing the commissioning phase. It scans the sky in a fixed wide strip centred at the declination of and works in Time Delay Integration (TDI) mode. We present a full catalog of sources in the ILMT str…
Chemodynamic Analysis of Four r-Process Enhanced Stars Observed with GTC
Sivarani, Thirupathi; Saraf, Pallavi
Here, we delineate a comprehensive abundance analysis of four r-process enhanced metal-poor stars observed with HORuS spectrograph on a 10-m class telescope, GTC. The high signal-to-noise ratio at R≈25000 spectral resolution allowed us to detect 16 light and 20 neutron-capture elements along with Th in two stars. Four of our program stars show sig…
Exploring Magnetic Coupling of Solar Atmosphere Through Frequency Modulations of 3-min Slow Magnetoacoustic Waves
Rawat, Ananya; Gupta, Girjesh
Coronal fan loops rooted in sunspot umbra show outward propagating waves with subsonic phase speed and a period around 3 min. However, their source region in the lower atmosphere is still ambiguous. We performed multi-wavelength observations of a clean fan loop system rooted in a sunspot utilizing data from the Interface Region Imaging Spectrograp…
Hot Stellar Populations of Berkeley 39 Using Swift/UVOT
Panthi, Anju; Vaidya, Kaushar; Chand, Komal +1 more
Open clusters are excellent tools to probe the history of the Galactic disk and properties of star formation. In this work, we present a study of an old age open cluster Berkeley 39 using the observations from UVOT instrument of the Neil Gehrels Swift observatory. Making use of a machine learning algorithm, ML-MOC, we have identified a total of 86…
Optical Polarisation Study of Galactic Open Clusters
Ganesh, Shashikiran; Prajapati, Prachi; Joshi, Santosh +3 more
Dust is a ubiquitous component in our Galaxy. It accounts for only 1% mass of the ISM but still is an essential part of the Galaxy. It affects our view of the Galaxy by obscuring the starlight at shorter wavelengths and re-emitting in longer wavelengths. Studying the dust distribution in the Galaxy at longer wavelengths may cause discrepancies due…
Gaps in the Main-Sequence of Star Cluster Hertzsprung-Russell Diagrams
Priya, Hasan
The presence of gaps or regions of small numbers of stars in the main sequence of the Hertzsprung-Russell Diagram (HRD) of star clusters has been reported in literature. This is interesting and significant as it could be related to star formation and/or rapid evolution or instabilities. In this paper, using Gaia DR3 photometry and confirmed member…
The Polstar UV spectropolarimetry mission
Ignace, R.; Scowen, P.
The Polstar small explorer concept is for an ultraviolet (UV) spectropolarimetry space telescope mission with a focus on massive star astrophysics. The instrument waveband will be from 115 nm to 286 nm for spectroscopy, and from 122 nm to 286 nm for polarimetry. All four Stokes parameters, I, Q, U, and V , will be measured at a resolving power of …
Survey of Variables with the ILMT
Kumar, Brajesh; Surdej, Jean; Negi, Vibhore +11 more
Nestled in the mountains of Northern India, is a 4-metre rotating dish of liquid mercury. Over a 10-year period, the International Liquid Mirror Telescope (ILMT) will survey 117 square degrees of sky, to study the astrometric and photometric variability of all detected objects. One of the scientific programs will be a survey of variable stars. The…
Insights on the Optical and Infrared Nature of MAXI J0709-159: Implications for High-Mass X-ray Binaries
Mathew, Blesson; Muneer, S.; Joshi, Santosh +4 more
In our previous study (Bhattacharyya et al., 2022), HD 54786, the optical counterpart of the MAXI J0709-159 system, was identified to be an evolved star, departing from the main sequence, based on comparisons with non-X-ray binary systems. In this paper, using color-magnitude diagram (CMD) analysis for High-Mass X-ray Binaries (HMXBs) and statisti…