Search Publications
Classification and disk parameters of Herbig Ae/Be stars using WISE and AKARI data
Subramaniam, Annapurni; Adara, B.
We present the classification and disk parameters of 50 Herbig Ae/Be stars using WISE and AKARI data. These stars have been classified into 4 groups based on the scheme proposed by Koenig et al. (2012) using WISE pass bands and by constructing their SEDs using data up to 12 pass bands. We could successfully classify 18 sources as Class I, 22 as Cl…
Spectroscopy of novae -- a user's manual
Shore, Steven N.
The spectroscopic development of classical novae is described as a narrative of the various stages of the outburst. The review highlights the multiwavelength aspects of the phenomenology and the recent developments related to structure, inhomogeneity, and dynamics of the ejecta. Special emphasis is placed on the distinct behavior of the symbiotic-…
Observations of classical and recurrent novae with X-ray gratings
Orio, M.
X-ray grating spectra have opened a new window on nova physics. High signal-to-noise spectra have been obtained for 12 novae after the outburst in the last 13 years, with the Chandra and XMM-Newton gratings. They offer the only way to probe the temperature, effective gravity and chemical composition of the hydrogen burning white dwarf before it tu…
High-resolution spectroscopy and high-density monitoring in X-rays of novae
Ness, J. U.
The 21st century X-ray observatories XMM-Newton, Chandra, and Swift gave us completely new insights into the X-ray behaviour of nova outbursts. These new-generation X-ray observatories provide particularly high spectral resolution and high density in monitoring campaigns, simultaneously in X-rays and UV/optical. The entire evolution of several nov…
Investigation of variability of iron emission lines in Centaurus X-3
Paul, Biswajit; Naik, Sachindra
We present the results obtained from a study of the variability of iron emission lines in the high mass X-ray binary pulsar Cen~X-3 during the eclipse, eclipse-egress and out-of-eclipse phases using XMM-Newton observations. Three iron emission lines at 6.4 keV, 6.7 keV, and 6.97 keV are clearly detected in the spectrum of the pulsar during the ent…
Simultaneous X-ray and optical observations of thermonuclear bursts in the LMXB EXO 0748-676
Paul, Biswajit; Saripalli, Lakshmi; Archana, M.
We report the detection of a large number of optical bursts in the Low Mass X-ray Binary (LMXB) EXO 0748-676 simultaneous with the thermonuclear X-ray bursts. The X-ray and the optical bursts are detected in a long observation of this source with the XMM-Newton observatory. This has increased the number of thermonuclear X-ray bursts in the LMXBs w…
Photometric parameters, distance and period-colour study of contact binary stars in the globular cluster ω Centauri
Sriram, K.; Vivekananda Rao, P.; Kiron, Y. Ravi
We present V passband photometric solutions of six contact binaries in the globular cluster ω Centauri using the Wilson-Devinney code. We found that four of the systems are H subtype W UMa binary systems and remaining two are W-subtype W UMa systems. Four of the systems show the O'Connell effect in their light curves and brightness at 0.75 phase i…
Comparison of energies between eruptive phenomena and magnetic field in AR 10930
Ravindra, B.; Howard, Timothy A.
We present a study comparing the energy carried away by a coronal mass ejection (CME) and the radiative energy loss in associated flare plasma, with the decrease in magnetic free energy during a release in active region NOAA 10930 on December 13, 2006 during the declining phase of the solar cycle 23. The ejected CME was fast and directed towards t…
Estimation of C II and C II* column densities along Galactic sight-lines
Sofia, Ulysses J.; Babu, B. R. S.; Murthy, Jayant +1 more
We present interstellar C II (1334.5323 Å) and C II* (1335.7077 Å) column density measurements along 14 Galactic sight-lines. These sight-lines sample a variety of Galactic disk environments and include paths that range nearly two orders of magnitude in average hydrogen densities (<n(H)>) along the lines of sight. Five of the sight-lines sho…
Study of Bubble nebula using IUE high resolution spectra
Murthy, Jayant; Anand, M. Y.; Kagali, B. A.
In this paper, we have analyzed IUE high resolution spectra of the central star (BD+602522) of the Bubble nebula. We discuss velocities of the different regions along the line of sight to the bubble. We find that the Bubble nebula is younger (by a factor of 100) than the exciting star suggesting that either the bubble is expanding into an inhomoge…