N. S. Singh

Manipur University, Imphāl, State of Manipur, India

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Publications (3)7.1 Total impact

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    ABSTRACT: A nonlinear nature of the binary ephemeris of Cygnus X-3 indicates either a change in the orbital period or an apsidal motion of the orbit. We have made extended observations of Cygnus X-3 with the Pointed Proportional Counters (PPCs) of the Indian X-ray Astronomy Experiment (IXAE) during 1999 July 3-13 and October 11-14. Using the data from these observations and the archival data from ROSAT, ASCA, BeppoSAX and RXTE, we have extended the data base for this source. Adding these new arrival time measurements to the published results, we make a comparison between the various possibilities, (a) orbital decay due to mass loss from the system, (b) mass transfer between the stars, and (c) apsidal motion of the orbit due to gravitational interaction between the two components. Orbital decay due to mass loss from the companion star seems to be the most probable scenario. Comment: 7 pages, 4 figures, accepted for publication in A&A
    Astronomy and Astrophysics 06/2002; · 5.08 Impact Factor
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    ABSTRACT: The X-ray binary Cygnus X-3 was observed with the Indian X-ray Astronomy Experiment (IXAE) on Board the Indian Remote Sensing Satellite IRS-P3 during July 3-13, 1999 and October 11-24, 1999 with total useful exposure time of 31244.64 seconds in 1 sec integration mode. The short and long time variability of this X-ray source has been studied. We have found the orbital period to be 17254.273 deg 0.890 seconds.
    Bulletin of the Astronomical Society of India 08/2001; 29:351-354. · 0.83 Impact Factor
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    ABSTRACT: A nonlinear nature of the arrival time of the 4.8 hr binary modulation in the X-ray light curve of Cygnus X-3 indicates either a change in the orbital period or an apsidal motion of the orbit. We have made extended observations of Cygnus X-3 with the Pointed Proportional Counters of the Indian X-ray Astronomy Experiment during 1999 July 3–13 and and 199 October 11–24. Using these and archival data from ROSAT, ASCA, and RXTE we have extended the data base for this source. Adding these new arrival time measurements to the published results, we make a comparison between the various possibilities, (a) orbital expansion due to mass loss from the system, (b) mass transfer between the components, and (c) apsidal motion of the orbit due to gravitational interaction between the two components. Orbital expansion due to mass loss from the companion star seems to be the most probable scenario. Most possibly, the compact star in this system has an accretion disk with an extended corona.
    Advances in Space Research 01/2001; 28:405-409. · 1.18 Impact Factor