X-ray binary


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X-ray binary

The most common type of luminous galactic X-ray source, involving a close binary system in which gas flows (via the inner Lagrangian point) or blows (by a strong stellar wind) from a normal nondegenerate star on to a compact companion (see mass transfer; binary star). For the most luminous sources such as Centaurus X-3 and Cygnus X-1, radiating X-rays at 1029–1031 watts, this companion is probably a neutron star or black hole; in less luminous cases, such as SS Cygni and AM Herculis, it is more likely to be a white dwarf. Gravitational energy powers these sources and both the luminosity (L) and temperature (T) are proportional to the mass-to-radius ratio (M /R) of the accreting star:
L ∝ (M /R )Gm
where G is the gravitational constant and m ′ is the rate of mass accretion, and
T ∝ (M/R )G
where ∊ depends on the efficiency of the gas heating, being high for shocks and low for viscous heating.

Two main types of X-ray binary are distinguished: in high-mass binaries (HMXBs), such as Centaurus X-3 and Cygnus X-1, the nondegenerate star is a giant or supergiant of early spectral type (O, B, or A); in low-mass binaries (LMXBs) such as Hercules X-1, the visible star is a middle or late main-sequence star of near solar mass. Several binaries contain a pulsating X-ray source, probably involving a rotating magnetized neutron star; these binaries, which include Centaurus X-3 and Hercules X-1, are among the best-determined of all binary systems.

The most luminous X-ray binaries, including Cygnus X-3, Scorpius X-1, and Circinus X-1, are also strong variable radio sources, sometimes also emitting radio flares.

x-ray binary

[′eks ‚rā ′bī‚ner·ē]
(astronomy)
An x-ray source that is a member of a binary system.
References in periodicals archive ?
Since only the brightest X-ray binaries would be visible even to Chandra at this short distance from Sgr A*, the team postulated that a much larger population - at least 300, going up to as many as 1,000 - of fainter X-ray binary systems could be floating around the central supermassive black hole.
The researchers suggest that the properties and spatial distribution of these x-ray binary systems point to a total population of hundreds of black holes associated with binary systems within a parsec of the centre, and many more isolated black holes.
This low mass X-ray binary is actually the brightest X-ray source in the sky other than the Sun or the diffuse X-ray background radiation and estimation from XMM-Newton instrument in the range 2-10 keV are according to [15]
(1999) The broad band spectral properties of galactic X-ray binary pulsars.
Heinz asserted that X-ray binaries provide us with opportunities to study matter under extreme conditions that would be impossible to recreate in a laboratory, saying that for the first time, they can study a newly minted neutron star in an X-ray binary system.
X-ray binary stars are usually subdivided into two categories:
Analyses of these data are already sufficient to invalidate some ideas about X-ray binary formation.
During the initial mass-transfer stage, the system would qualify as a low-mass X-ray binary; with a slower-spinning neutron star emitting X-ray pulses as hot gas raced toward its surface.
From these dips, an orbital period of just 2.4 hours was measured, setting a new record for black hole X-ray binary systems.
Scientists hope to measure the spins of black holes in X-ray binary stars--a key topic in current discussions of black-hole evolution--as well as the geometry of neutron stars' intense magnetic fields.
Charles and his colleagues at the Royal Greenwich Observatory in the Canary Islands, Spain, to study the infrared spectra of the X-ray binary. Using the 4.2-meter William Herschel Telescope and a new, large-format infrared detector, the researchers found that helium alone accounted for the surprisingly intense infrared emissions from Cygnus X-3.
Located about 2.2 billion light-years from Earth, the small galaxy is home to over a dozen black holes and neutron stars that exist in "X-ray binary" systems.