1998/09/15 by J. Greiner, Jochen Greiner, Greiner, Jochen +3
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #High-pressure geophysics and materials #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9809192
4 pages (aa style) incl. 3 figures; to be publ. in Astronomy & Astrophysics; also available from http://www.obs.aip.de/~jcg/publis.html
arxiv created 1998/09/15 · openalex publication_date 1998/09/15 · arxiv updated 2009/12/01 · openalex created_date 2019/07/30 · openalex updated_date 2026/07/28
We investigate the ROSAT X-ray properties of V Sge, which has been proposed\nto be related to supersoft X-ray binaries. During optical bright states, V Sge\nis a faint hard X-ray source, while during optical faint states (V >=12 mag), V\nSge is a `supersoft' X-ray source. Spectral fitting confirms that V~Sge's X-ray\nproperties during its soft X-ray state may be similar to those of supersoft\nX-ray binaries, although a much lower luminosity cannot be excluded. It is\npossible to explain the different optical/X-ray states by a variable amount of\nextended uneclipsed matter, which during the optical bright states contributes\nsignificantly to the optical flux and completely absorbes the soft X-ray\ncomponent. An additional, perhaps permanent, hard X-ray component, such as a\nbremsstrahlung component with a 0.1-2.4 keV luminosity of ~1030 erg/s, must be\npresent to explain the X-ray properties during the optical bright/hard X-ray\nstate.\n