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麻州劍橋 ─ 根據自然期刊一篇報導，一顆正在死亡的恆星正在破壞自己的太陽系。
這顆編號WD 1145+017是一顆未於處女座的白矮星。今年三月，一名哈佛大學史密森尼中心天體物理學研究生Andrew Vanderburg首次發現。波士頓環球報報導，該顆白矮星是被NASA的克卜勒太空望遠鏡在執行太空船K2任務時發現。
Vanderburg 觀察到，每4個半小時，這顆白矮星上會發出一規律亮點。這表示有一物體當時在白矮星週遭運行，離白矮星約84萬公里遠，大約是地球至月球兩倍的距離。澳洲美國廣播公司報導，在分析完地面望遠鏡資料後Vanderburg 結論，這個亮點是因這顆行星受到白矮星的引力吸引，而在崩毀過程產生的訊號。
「我們捕捉到一顆恆星摧毀自己的系統，」Vanderburg 告訴波士頓環球報，「這一點十分確信。」
當一顆恆星核融合的能量被用盡後，恆星將會變成一顆巨大的紅巨星。紅巨星的高溫足以讓氦氣變成炭。 但是當氦氣用盡後，紅巨星便開始收縮，變成紅巨星燃燒剩下的地核殘渣，白矮星。
白矮星有極高的密度。 他的引力強大到可以摧毀圍繞運轉的行星。太空人相信當行星被拉出適居帶後，將會被白矮星強大的引力扯得支離破碎。
英文原文：
CAMBRIDGE, MASSACHUSETTS — A dying star is ripping apart planets in its own solar system, according to a team of astronomers who published a paper yesterday in the journal Nature.
The star, called WD 1145+017, is a white dwarf in the constellation Virgo. The finding was made by Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics, in March. The white dwarf was spotted by NASA’s Kepler space telescope as part of the spacecraft’s K2 mission, the Boston Globe reported.
Vanderburg saw a regular dip in brightness of the white dwarf every four-and-a-half hours. This suggested an object was orbiting the white dwarf at a distance of about 840,000 kilometres, about twice the distance between Earth and the Moon. After analysing data from the ground-based telescopes, Vanderburg concluded that the signal was caused by the disintegration process of the planet by the white dwarf’s gravitational pull, ABC Australia reported.
“We’ve caught a star in the act of destroying a planet in its own system,” Vanderburg told the Boston Globe. “It’s like the smoking gun.”
After a regular star uses up its nuclear fuel, it expands and turns into a red giant. Red giants are hot enough to convert helium into carbon. However, when its helium fuel has been exhausted, a red giant starts to contract and become more compact, eventually turning into a white dwarf, a leftover of the star’s inner core.
A white dwarf is extremely dense, and its gravitational pull is so enormous that it can tear an orbiting planet apart. Astronomers believe that when a planet orbits closer than the habitable zone, it can be disintegrated by the gravitational pull of a white dwarf.
