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X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', which is compact: a white dwarf, neutron star, or black hole. The infalling matter releases gravitational potential energy, up to several tenths of its rest mass, as X-rays. The lifetime and the mass-transfer rate in an X-ray binary depends on the evolutionary status of the donor star, the mass ratio between the stellar components and their orbital separation.〔Tauris & van den Heuvel (2006), "Formation and evolution of compact stellar X-ray sources", (In: Compact stellar X-ray sources. Edited by Walter Lewin & Michiel van der Klis. Cambridge Astrophysics Series, p.623-665, DOI: 10.2277/0521826594 )〕 (Hydrogen fusion releases only about 0.7 percent of rest mass.) An estimated 1041 positrons escape per second from a typical hard low-mass X-ray binary.〔 ("Mystery of Antimatter Source Solved – Maybe" ) by John Borland 2008 〕 ==Classification== X-ray binaries are further subdivided into several (sometimes overlapping) subclasses, that perhaps reflect the underlying physics better. Note that the classification by mass (high, intermediate, low) refers to the optically visible donor, not to the compact X-ray emitting accretor. * Low-mass X-ray binaries (LMXBs) * * Soft X-ray transients (SXTs) * * Symbiotic X-ray binaries * * Super soft X-ray sources or Super soft sources〔(Introduction to Cataclysmic Variables (CVs) ), NASA, 2006.〕 (SSSs),(SSXB) * Intermediate-mass X-ray binaries (IMXBs) * High-mass X-ray binaries (HMXBs) * * Be/X-ray binaries (BeXRBs) * * Supergiant X-ray binaries (SGXBs) * * Supergiant Fast X-ray Transients (SFXTs)〔(Negueruela et al., 2005 ''Supergiant Fast X-ray Transients: A new class of high mass X-ray binaries unveiled by INTEGRAL'' )〕〔(L. Sidoli, 2008 ''Transient outburst mechanisms'' )〕 * Others * * X-ray bursters * * X-ray pulsars * * Microquasars (radio-jet X-ray binaries that can house either a neutron star or a black hole) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「X-ray binary」の詳細全文を読む スポンサード リンク
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