Tracking the path of a black hole. (Astronomy).Astronomers have for the first time measured the motion of a small black hole 1. black hole - An expression which depends on its own value or a technique to detect such expressions. In graph reduction, when the reduction of an expression is begun, the root of the expression can be overwritten with a black hole. If the expression depends on its own value, e.g. x = x + 1 then it will try to evaluate the black hole which will usually print an error message and abort the program. and a companion star speeding through our galactic neighborhood. The black hole and the star that it's slowly devouring travel together on a looping path that ultimately will take them toward the outer reaches of our galaxy. In the Sept. 13 NATURE, researchers argue that the black hole, which is the compact remains of a massive star, was ejected from a star cluster. Ever since, it has been wandering the galaxy along with its stellar companion, the scientists propose. Known as XTE XTE - Cross Track Error XTE - X-Ray Timing Explorer J1118+480, the duo was discovered last year by NASA's Rossi X-ray Timing Explorer satellite. Studies of its radio emissions reveal that the black hole-star combo qualifies as a miniature version of a quasar. Material snared by the black hole from its companion has formed a swirling disk around the hole. Jets of subatomic 1. Of or relating to the constituents of the atom. 2. Having dimensions or participating in reactions characteristic of the constituents of the atom. Because of the pair's proximity to Earth, astronomers were able to track the motion of the black hole and its partner with the Very Large Baseline Array, a network of radio telescopes that stretches from Hawaii to the U.S. Virgin Islands. The duo zips through space at 145 kilometers a second, notes study coauthor I. Felix Mirabel, who is affiliated with both the Institute for Astronomy and Space Physics in Buenos Aires and the French Atomic Energy Commission Atomic Energy Commission (AEC), former U.S. government commission created by the Atomic Energy Act of 1946 and charged with the development and control of the U.S. atomic energy program following World War II. At the time, debate centered around the question of whether the commission should be predominantly military or civilian. in Gif-sur-Yvette, France. The orbit of XTE J1118+480 resembles that of globular clusters globular cluster: see star cluster., large groupings of the oldest stars in the galaxy. Unlike most stars in the Milky Way Milky Way, the galaxy of which the sun and solar system are a part, seen as a broad band of light arching across the night sky from horizon to horizon; if not blocked by the horizon, it would be seen as a circle around the entire sky. Although its motion is not readily apparent, the entire galaxy is rotating about the Milky Way's center. Relative to the universe, the galaxy is moving at a speed of c.370 mi per sec (c., globular clusters don't reside within the galaxy's plane. Instead, they orbit the Milky Way's center along paths that take them below and above the plane. The similar orbit of the black hole suggests that it long ago received a strong kick that expelled it from a globular cluster or from a region within the Milky Way's disk. Simulations of that event suggest that a globular cluster is the most likely source of the black hole. The massive star that collapsed to become the black hole "probably formed in a globular cluster even before our galaxy's disk was formed," Mirabel says. The observations therefore mark "the intense burst of star formation that took place during an early stage of our galaxy's development," he says. --R.C. |
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