A small-scale X-ray binary star (LMXB, abbreviation of English Low-Mass X-ray binary) is a double star in which one of the components is either a black hole or a neutron star. The other component, donor of matter, usually fills the Roche lobe of the first and often transfers the mass to the compact star. The donor star is less massive than the compact object he has for companion, and may also be on the main sequence, or be a star degenerate (white dwarf), or an evolved star (red giant). About one hundred X-ray stars were discovered in the Milky Way, and thirteen of them were found in globular clusters. New data from the Chandra Telescope have detected twin X-ray stars also in distant galaxies. A typical double-ray star emits much of its electromagnetic radiation in the X-ray, and usually only less than one percent in visible light, so it is one of the brightest objects in the X-ray sky, but relatively weak in visible light; the apparent magnitude is typically between +15 and +20. The brightest part of the system is the growing disk around the compact object. The orbital period may vary depending on the system, from a minimum of ten minutes to a maximum of a few hundred days. Voices correlateemodify wikitesto
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