Crust on a star.By analyzing X rays generated by the rumblings of a neutron star neutron star, extremely small, extremely dense star, about double the sun's mass but only a few kilometers in radius, in the final stage of stellar evolution. Astronomers Baade and Zwicky predicted the existence of neutron stars in 1933. 40,000 light-years from Earth, astronomers have estimated the thickness of the dense star's crust. In December 2004, spacecraft including NASA's Rossi X-ray Timing Explorer The Rossi X-ray Timing Explorer (RXTE) satellite observes the fast-moving, high-energy worlds of black holes, neutron stars, X-ray pulsars and bursts of X-rays that light up the sky and then disappear forever. detected the brightest X-ray flash ever seen from beyond the solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. (SN: 2/26/05, p. 132). The radiation came from an explosion on the neutron star SGR SGR Sustainable Growth Rate SGR Societa' di Gestione del Risparmio (Italian: Investment Management Company) SGR Specific Growth Rate SGR Surgeon General's Report SGR Soft Gamma-ray Repeater 1806-20. Intensity fluctuations within the flash were probably generated by seismic vibrations traveling along different paths within the star's iron crust, according to astronomers led by Tod Strohmayer of NASA's Goddard Space Night Center in Greenbelt, Md. X rays of some frequencies would have come from seismic waves on twisting paths around the star's circumference, while other X rays were probably generated by vibrations on a more direct path through the crust. If a previous estimate is correct that the neutron star is about 20 kilometers across, then the crust is about 1.6 km thick, the team announced last month at a meeting of the American Physical Society The American Physical Society was founded in 1899 and is the world's second largest organization of physicists. The Society publishes more than a dozen science journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than twenty science in Dallas. That thickness supports theoretical models in which neutron stars consist of ordinary matter. A star made of exotic subatomic particles would form a much thicker crust, according to some models. |
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