oscar 2009-3-21 10:10
來自白矮星蛇夫座RS的新星爆發
Explosions from White Dwarf Star RS Oph
[img]http://i12.tinypic.com/2nir3ax.jpg[/img]
圖示版權與提供: David A. Hardy & PPARC
[color=navy]Explanation: [/color]
Spectacular explosions keep occurring in the binary star system named RS Ophiuchi. Every 20 years or so, the red giant star dumps enough hydrogen gas onto its companion white dwarf star to set off a brilliant thermonuclear explosion on the white dwarf's surface. At about 2,000 light years distant, the resulting nova explosions cause the RS Oph system to brighten up by a huge factor and become visible to the unaided eye. The red giant star is depicted on the right of the above drawing, while the white dwarf is at the center of the bright accretion disk on the left. As the stars orbit each other, a stream of gas moves from the giant star to the white dwarf. Astronomers speculate that at some time in the next 100,000 years, enough matter will have accumulated on the white dwarf to push it over the Chandrasekhar Limit, causing a much more powerful and final explosion known as a supernova.
[color=navy]說明: [/color]
在名為蛇夫座RS (RS Ophiuchi)的雙星系統裡，壯觀的爆炸不停的重覆發生。大約每隔20年，隨著紅巨星傾洩足夠的氫氣到它的白矮伴星，就會在白矮星的表面引發閃亮的熱融合爆炸。讓離我們有二千光年遠的蛇夫座RS星，因新星爆炸而大幅增亮，成為肉眼可見的天體。在上面這幅圖示中，右方的天體就是這顆紅巨星，白矮星則位在左端明亮吸積盤的中心。隨著恆星相互繞行，雲氣不斷地由紅巨星流向白矮星。天文學家認為在接下來十萬年的某個時間點，當足夠的質量累積在白矮星上，讓它的質量超過錢氏極限 (Chandrasekhar Limit)時，就會造成更強烈的超新星爆炸。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]