小行星4388将于北美山区标准时间18日晚上遮蔽天狼星。图为2005年12月18日,NASA所拍摄到的天狼星,其中包括天狼星A和天狼星B(左下方比较小颗)。(HO/NASA/AFP)nighttime sky, along with its faint, tiny stellar companion, Sirius B(lower-L). The cross-shaped diffraction spikes and concentric rings around Sirius, and the small ring around Sirius B, are artifacts produced within the telescope's imaging system. Sirius B is a white dwarf that orbits around Sirius every 50 years. Sirius, located in the winter constellation Canis Major, is 8.6 light-years from Earth. An international team of astronomers has used the keen eye of NASA's Hubble Space Telescope to isolate the light from the white dwarf, called Sirius B. The new results allow them to measure precisely the white dwarf's mass based on how its intense gravitational field alters the wavelengths of light emitted by the star. AFP PHOTO/HO/NASA (Photo by HO / NASA / AFP)
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