X-ray Binary

Close binary systemDefinable part of the universe that can be open, closed, or isolated. An open system exchanges both matter and energy with its surroundings. A closed system can only exchange energy with its surroundings; it has walls through which heat can pass. An isolated system cannot exchange energy or matter with where a neutron starDense ball of neutrons that remains at the core of a star after a supernova explosion has destroyed the rest of a star with mass 8-18 (?) Msun. A neutron star has mass ~2-3 Msun, density ~1014 g/cm3, and is supported by neutron degeneracy pressure. Typical neutron stars are 10-20 (or rarely a black holeMaximally gravitationally collapsed object predicted to exist by the theory of general relativity, from which no material object, light or signal of any kind can escape. Many black holes form when a high mass supergiant star explodes in a supernova explosion at the end of its life. A star probably) accretes matter from what is usually a main sequence starSelf-luminous object held together by its own self-gravity. Often refers to those objects which generate energy from nuclear reactions occurring at their cores, but may also be applied to stellar remnants such as neutron stars. (left). X-ray binaries are some of the most luminous X-ray sources in the sky. X-raysHigh-energy electromagnetic radiation, with short wavelength (~10-0.01 nm) and high frequency (greater than ~1016 Hertz). Although the boundaries are somewhat arbitrary, wavelengths shorter than 0.01 nm are called gamma-rays and those longer than 10 nm extreme ultraviolet (EUV). X-rays would be produced by blackbody radiation at temperatures in excess of are produced as material from the companion star is drawn to the compact object either through Roche-lobe overflow into an accretion diskDisk-shaped cloud of gas and solids in orbital motion around a central protostar or some other massive central body. (low-mass X-ray binaries) or through direct impact of a stellar windFast continuous outflow of material (p+, e–, and atoms of heavier metals) ejected from stars. Stellar winds are characterized by speeds of 20–2,000 km/sec. The causes, ejection rates and speeds of stellar winds vary with the mass of the star. In relatively cool, low-mass stars, such as the Sun, the onto the compact object (high-mass X-ray binaries).

Modified from image source: http://chandra.harvard.edu/photo/2002/xtej1550/.