南门二: 离我们最近的恒星系统

南门二: 离我们最近的恒星系统

Alpha Centauri: The Closest Star System
Image Credit & Copyright: Telescope Live, Heaven’s Mirror Observatory; Processing: Chris Cantrell

Explanation: The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest — called Proxima Centauri — is actually the nearest star. The bright stars Alpha Centauri A and B form a close binary as they are separated by only 23 times the Earth- Sun distance – slightly greater than the distance between Uranus and the Sun. The Alphasystem is not visible in much of the northern hemisphere. Alpha Centauri A, also known as Rigil Kentaurus, is the brightest star in the constellation of Centaurus and is the fourth brightest star in the night sky. Sirius is the brightest even though it is more than twice as far away. By an exciting coincidence, Alpha Centauri A is the same type of star as our Sun, and Proxima Centauri is now known to have a potentially habitable exoplanet.

Tomorrow’s picture: 2024 in the sun

南门二: 离我们最近的恒星系统
影像提供与版权: Telescope Live, Heaven’s Mirror Observatory; 影像处理: Chris Cantrell

说明: 离太阳最近的恒星近邻是南门二系统。在这个三合星里，离太阳最近的是其中最昏暗的比邻星。而明亮的南门二A与B，是密近的双星，间距只有地球和太阳距离的23倍，只比天王星和太阳的间距要大上一些而已。不过，对大部分的北半球来说，只有近赤道地区才能见到南门二恒星系统。在这组三合星里，最明亮的是专名为南门二的南门二A；它除了是半人马座的最亮星之外，也是地球夜空中的第四亮星。天狼星则拥有最亮星的头衔，纵然它的距离是南门二的2倍之多。很巧的是，南门二和我们太阳是同类型的恒星，而比邻星更是拥有一颗可能适居的系外行星。（Alpha Centauri 南门二系统、半人马α; Proxima Centauri 比邻星; Rigil Kentaurus 南门二A、南门二）

明日的图片: 2024 in the sun

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