TYPES OF STAR STELLAR ASTROPHYSICS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site microquasar An object of stellar mass that displays in miniature some of the properties of quasars, including strong emission across a broad range of wavelengths from radio wave to X-ray, rapid variability in X-rays, and radio jets. A microquasar consists of a binary system in which a normal star orbits around, and loses matter to, a nearby compact object, either a black hole or a neutron star. The lost matter enters a fast-spinning accretion disk, is heated to millions of degrees, and then either falls onto the compact object or is ejected as a bipolar flow. A dozen or so microquasars have been found in the Milky Way Galaxy. One of them, known as GRS 1915+105, lies 40,000 light-years away in Aquila and was discovered in 1994 by the GRANAT X-ray satellite. It consists of an ordinary star with about the same mass as the Sun orbiting around the heaviest stellar black hole found to date, with a mass of 14 solar masses. In its year of discovery, it was observed to shoot out material with one-third the mass of the Moon in opposite directions at 92% of the speed of light. Another microquasar, LS 5039, is much closer, at a distance of only 9,100 light-years, has twin radio-bright jets, each about 2.6 billion km long, but is surprisingly dim in X-rays, suggesting that future searches might reveal many more such X-ray-dim objects. If so, it may be that microquasars are a substantial, if not dominant, source of high-energy particles and radiation in the Galaxy. The closest known microquasar and black hole to Earth is V4641 Sagittarii, which lies only about 1,500 light-years away. Related categories    • TYPES OF STAR    • STELLAR ASTROPHYSICS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP