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❪◑❫ LMXB ○｜Definition｜1st｜20260110205401-00-⌔

X-ray binary - Wikipedia#Low-mass_X-ray_binary

Low-mass X-ray binary

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A low-mass X-ray binary (LMXB) is a binary star system where one of the components is either a black hole or neutron star.1 The other component, a donor, usually fills its Roche lobe and therefore transfers mass to the compact star. In LMXB systems the donor is less massive than the compact object, and can be on the main sequence, a degenerate dwarf (white dwarf), or an evolved star (red giant). Approximately two hundred LMXBs have been detected in the Milky Way,2 and of these, thirteen LMXBs have been discovered in globular clusters. The Chandra X-ray Observatory has revealed LMXBs in many distant galaxies.3

A typical low-mass X-ray binary emits almost all of its radiation in X-rays, and typically less than one percent in visible light, so they are among the brightest objects in the X-ray sky, but relatively faint in visible light. The apparent magnitude is typically around 15 to 20. The brightest part of the system is the accretion disk around the compact object. The orbital periods of LMXBs range from ten minutes to hundreds of days.

The variability of LMXBs are most commonly observed as X-ray bursters, but can sometimes be seen in the form of X-ray pulsars. The X-ray bursters are created by thermonuclear explosions created by the accretion of Hydrogen and Helium.4

Printed 2026-06-28.

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Footnotes

  1. Tauris, Thomas M.; van den Heuvel, Ed (2006). “Chapter 16: Formation and evolution of compact stellar X-ray sources”. In Lewin, Walter; van der Klis, Michiel (eds.). Compact Stellar X-ray Sources. Cambridge Astrophysics Series. Vol. 39. pp. 623–665. arXiv:astro-ph/0303456. Bibcode:2006csxs.book..623T. doi:10.1017/CBO9780511536281.017. ISBN 978-0-521-82659-4. S2CID 18856214. ↩

  2. Liu, Q. Z; Van Paradijs, J; Van Den Heuvel, E. P. J (2007). “A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)”. Astronomy and Astrophysics. 469 (2): 807. arXiv:0707.0544. Bibcode:2007A&A…469..807L. doi:10.1051/0004-6361:20077303. S2CID 14673570. ↩

  3. Tetarenko, B. E.; Sivakoff, G. R.; Heinke, C. O.; Gladstone, J. C. (February 10, 2010). “Watchdog: A Comprehensive All-Sky Database of Galactic Black Hole X-Ray Binaries”. The Astrophysical Journal Supplement Series. 222 (2): 15. arXiv:1512.00778. doi:10.3847/0067-0049/222/2/15. S2CID 118833989. ↩

  4. Tauris, Thomas M; Van Den Heuvel, Edward P. J; Savonije, Gerrit J (2000). “Formation of Millisecond Pulsars with Heavy White Dwarf Companions:Extreme Mass Transfer on Subthermal Timescales”. The Astrophysical Journal. 530 (2): L93–L96. arXiv:astro-ph/0001013. Bibcode:2000ApJ…530L..93T. doi:10.1086/312496. PMID 10655173. S2CID 17772120. ↩

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