G. Selvakumar

G. Selvakumar
Indian Institute of Astrophysics | IIAP · Research Division Stellar and Galactic Astronomy

M.Sc ., M.Phil

About

24
Publications
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Introduction

Publications

Publications (24)
Article
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/Gas Slit Camera observations in soft and hard X-rays from MAXI J0709–159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 1037 erg s−1 (MAXI), which got reduced to 1032 erg s−1 (NuSTAR) after the flare....
Article
Full-text available
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/Gas Slit Camera observations in soft and hard X-rays from MAXI J0709–159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 10 ³⁷ erg s ⁻¹ (MAXI), which got reduced to 10 ³² erg s ⁻¹ (NuSTAR) after the fl...
Preprint
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/GSC observations in soft and hard X-rays from MAXI J0709-159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 10^(37) erg/s (MAXI), which got reduced to 10^(32) erg/s (NuSTAR) after the flare. We took l...
Article
We study the formation and the kinematic evolution of the early type Herbig Be star IL Cep and its environment. The young star is a member of the Cep OB3 association, at a distance of 798±9 pc, and has a ”cavity” associated with it. We found that the B0V star HD 216658, which is astrometrically associated with IL Cep, is at the center of the cavity...
Preprint
Full-text available
We study the formation and the kinematic evolution of the early type Herbig Be star IL Cep and its environment. The young star is a member of the Cep OB3 association, at a distance of 798$\pm$9 pc, and has a "cavity" associated with it. We found that the B0V star HD 216658, which is astrometrically associated with IL Cep, is at the center of the ca...
Article
Full-text available
The optical spectroscopic observations of ASASSN-18fv observed from 2018 March 24 to 2019 January 26 are presented. The optical spectra are obtained from Mirranook, Vainu Bappu, and South African Astronomical observatories. The spectra are dominated by the hydrogen Balmer, Fe ii, and O i lines with P-Cygni profiles in the early phase, typical of an...
Preprint
Full-text available
The optical spectroscopic observations of ASASSN-18fv observed from 2018 March 24 to 2019 Jan 26 are presented. The optical spectra are obtained from Mirranook, Vainu Bappu and South African Astronomical observatories. The spectra are dominated by hydrogen Balmer, Fe II and O I lines with P-Cygni profiles in the early phase, typical of an Fe II cla...
Article
Aims . We aim to study the spectroscopic and ionized structural evolution of T Pyx during its 2011 outburst, and also study the variation in degree of polarization during its early phase. Methods . Optical spectroscopic data of this system obtained from day 1.28–2415.62 since discovery, and optical, broadband imaging polarimetric observations obtai...
Preprint
Full-text available
We study the spectroscopic and ionized structural evolution of T Pyx during its 2011 outburst, and also study the variation in degree of polarization during its early phase. Optical spectroscopic data of this system obtained from day 1.28--2415.62 since discovery, and optical, broadband imaging polarimetric observations obtained from day 1.36--29.3...
Article
During the 2014-2015 mutual events season, the Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE), Paris France, and the Sternberg Astronomical Institute (SAI), Moscow Russia, led an international observation campaign to record ground-based photometric observations of Galilean moon mutual occultations and eclipses. We focused on pro...
Article
Full-text available
Optical spectra of the 2006 outburst of RS Ophiuchi beginning one day after discovery to over a year after the outburst are presented here. The spectral evolution is found to be similar to that in previous outbursts. The early phase spectra are dominated by hydrogen and helium (I & II) lines. Coronal and nebular lines appear in the later phases. Em...
Article
Results of analysis of 23 events of the 2014-2015 mutual event series from the Vainu Bappu Observatory are presented. Our intensity distribution model for the eclipsed/occulted satellite is based on the criterion that it simulates a rotational light curve that matches the ground based light curve. Dichotomy in the scattering characteristics of the...
Article
Low resolution optical spectra of the recurrent nova V745 Sco were obtained with the 2.3m Vainu Bappu Telescope and the OMR spectrograph from the Vainu Bappu Observatory (VBO). The spectra of February 7.99 UT and 9.99 UT were obtained in the 580-860nm wavelength region, while the spectrum of February 8.99 UT was obtained in the 340-580nm wavelength...
Article
Full-text available
Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. We search for metal-poor stars using the artificial neural network (ANN) and extend its usage to determine absolute magnitudes. We have constructed a library of 167 medium-resolution stellar spect...
Article
An abundance analysis has been conducted for a sample of nine post-AGB candidate stars; eight of them have not been explored before. We find four very promising objects like HD 105262, HD 53300 and CpD$-62^o5428$ among them. We find strong evidence of dust-gas separation through selective depletion of refractive elements in HD 105262. The same effe...
Conference Paper
Full-text available
We have undertaken to conduct a detailed comprehensive analysis of the chemical composition of a large sample of Ba and CH stars. Spectra of about 48 objects have been acquired so far. Preliminary results obtained from spectral analysis are presented.
Article
Full-text available
Context. In 2003, the Sun and the Earth passed through both the equatorial plane of Jupiter and therefore the orbital planes of its main satellites. Aims. During this period, mutual eclipses and occultations were observed and we present the data collected.Methods. Light curves of mutual eclipses and occultations were recorded by the observers of th...
Article
The recurrent nova RS Ophiuchi had its sixth recorded outburst on 2006 February 12, after an interval of 21 years. RS Ophiuchi is an interacting binary system with M2-3 giant secondary and an accreting, massive white dwarf primary. Recent results indicate this system to be a potential type Ia supernova progenitor. The latest outburst has been inte...
Article
Full-text available
CCD observations of the mutual events of the Galilean satellites of Jupiter from the Vainu Bappu Observatory during 1997 are presented. The derived times of close approach of the geometric centers of the satellites (satellite & shadow center) for the mutual occultations (mutual eclipses) are compared with the predictions. The residuals in observed...
Article
Full-text available
A large number of photographic (92) and CCD (27) spectra of the pole-on Be star, Mu Cen, were obtained between February 1987 and May 1990. From the results of the above-mentioned spectra a weak outburst was detected in March 1987 which was probably the fourth after the major outburst of this star in early February 1987. Recently, two major outburst...
Article
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