Supersoft X-ray source: Difference between revisions

Revision as of 16:54, 20 February 2018

Revision as of 16:55, 20 February 2018

Line 33:

"Cataclysmic variables (CVs) are close binary systems consisting of a white dwarf and a red-dwarf secondary transferring matter via the Roche lobe overflow."<ref name=Kato>{{ cite journal |author=Kato T|author2=Ishioka R|author3=Uemura M |title=Photometric Study of KR Aurigae during the High State in 2001 |journal=Publ. Astron. Soc. Jpn. |volume=54 |issue=6 |date=Dec 2002 |pages=1033–9 |url=http://pasj.asj.or.jp/v54/n6/540624/540624-frame.html |arxiv = astro-ph/0209351 |bibcode = 2002PASJ...54.1033K |doi=10.1093/pasj/54.6.1033}}</ref> Both fusion- and accretion-powered cataclysmic variables have been observed to be [[X-ray]] sources.<ref name=nasa2>{{ cite web |title=Introduction to Cataclysmic Variables (CVs) |url=http://heasarc.gsfc.nasa.gov/docs/objects/cvs/cvstext.html }}</ref> The accretion disk may be prone to [[instability]] leading to [[dwarf nova]] outbursts: a portion of the disk material falls onto the white dwarf, the cataclysmic outbursts occur when the [[density]] and [[temperature]] at the bottom of the accumulated hydrogen layer rise high enough to ignite [[nuclear fusion]] reactions, which rapidly burn the hydrogen layer to helium.

Apparently the only SSXS nonmagnetic cataclysmic variable is [[V SgeSagittae]]: bolometric luminosity of (1 - 10) x 10³⁷, a binary including a blackbody (BB) accretor at T < 80 eV, and an orbital period of 0.514195 d.<ref name=Greiner/>

The accretion disk can become thermally stable in systems with high mass-transfer rates (Ṁ).<ref name=Kato/> Such systems are called nova-like (NL) stars, because they lack outbursts characteristic of dwarf novae.<ref name=Osaki>{{ cite journal |doi=10.1086/133689 |last1=Osaki |first1=Yoji |title=Dwarf-Nova Outbursts |journal=Publ. Astron. Soc. Pac. |date=1996 |volume=108 |pages=39 |bibcode=1996PASP..108...39O }}</ref>