Astronomers witness never-before-seen asteroid break-up

Astronomers witness never-before-seen asteroid break-up

天文学家首次"目睹"小行星分裂

Astronomers said Thursday they have witnessed for the first time the breakup of an asteroid, disintegrating into as many as 10 smaller pieces at a "leisurely" speed.

天文学家3月6日报告称,他们首次观测到一颗小行星分裂正以"慢悠悠的"速度裂解成差不多10块碎片. 

The crumbling asteroid, designated P/2013 R3, was first noticed as an unusual, fuzzy-looking object by ground-based telescopes in Arizona on September 15, 2013, the researchers reported in the US journal Astrophysical Journal Letters.

这颗编号为P／2013　R3的小行星是2013年9月首次被亚利桑那州的地面望远镜发现的, 它看上去有些"模模糊糊、不同寻常".这一发现发表在新一期《天体物理学杂志通讯》上. 

A follow-up observation on Oct. 1 with the W. M. Keck Observatory on the summit of Mauna Kea, a dormant volcano on the island of Hawaii, revealed three bodies moving together in an envelope of dust nearly the diameter of Earth.

天文学家们在10月1日利用夏威夷的凯克天文台进一步观测发现,在一团直径与地球相当的尘埃中,有3块碎片.

Astronomers then looked at it with the Hubble Space Telescope, which soon showed there were really 10 embedded objects, each with comet-like dust tails, said David Jewitt of the University of California at Los Angeles, who led the astronomical forensics investigation.

研究负责人、美国加州大学洛杉矶分校教授戴维·朱伊特说,他们认为值得进一步研究,于是改用精度极高的哈勃太空望远镜进行观测,很快发现这颗小行星正在裂解成约10块碎片,而且每块都有彗星一样的尾巴.

The four largest rocky fragments are up to 400 yards (365.76 m) in diameter, about four times the length of a football field, Jewitt said. "Seeing this rock fall apart before our eyes is pretty amazing."

其中最大的4块碎片直径近365米,有4两个足球场那么长.朱伊特说："看着这颗小行星在我们眼前分裂,感觉真是非常奇妙！" 

The asteroid began coming apart early last year, and the researchers said the fragments are drifting away from each other at a leisurely pace of one mile (about 1.6 kilometer) per hour.

这颗小行星从去年年初开始分裂,远离彼此的相对速度只有"慢悠悠的每小时1.6公里".

The researchers said the rare event is not caused by a collision with another asteroid, or the pressure of interior ices warming and vaporizing. 

研究人员还表示这颗小行星发生分裂不是因为与另一颗小行星发生碰撞, 也不可能是因为有内部冰层升温挥发导致小行星承受不住压力而分裂. 

They suspected the break-up is a result of sunlight, which causes the rotation rate of the asteroid to gradually increase. Eventually, its component pieces succumb to centrifugal force and gently pull apart, "like grapes on a stem", they said. 

他们猜测,这颗小行星发生分裂是由于吸收阳光后自转速度逐渐加快,最后在离心力作用下,小行星开始缓慢分裂.  

The possibility of disruption in this manner, known as the YORP effect, has been discussed by scientists for several years, but never reliably observed. 

多年来,科学家一直猜想小行星会以这种"亚尔科夫斯基效应"的方式分裂,但此前从未观测到这种情况发生. 

The asteroid's remnant debris, weighing about 200,000 tons, will in the future provide a rich source of meteoroids, Jewitt said. 

朱伊特表示,这颗总重20万吨的小行星最终将会成为流星体的丰富来源. 

Most will eventually plunge into the sun, but a small fraction of the debris may one day blaze across our skies as meteors, he added.