彗星57P已经分裂成19块，天文学家关注又一串“太空项链”。（有图）（摘自美国CNN有线

Comet crumbles into spectacular debris trail

By Richard Stenger
CNN

(CNN) -- Sweltering in the heat of the sun, a comet in the inner solar system has broken into a glistening string of at least 19 icy boulders, astronomers said.

Other disintegrating comets have been imaged, but they consisted of only a handful of chunks. None boasted nearly as many pieces, the University of Hawaii research team said.

The scientists knew that comet 57P had split, but were shocked to find so many parts when they looked at it with a telescope on the summit of the highest mountain in Hawaii.

"We guessed that we could find some more fragments but we didn't guess that we'd find so many. It's quite awesome," said David Jewitt, who with two colleagues watched the comet on two nights last week.

They speculate that comet 57P suffered a significant catastrophe in the recent past, "violent enough to break off many pieces of its nucleus."

The event was likely caused by sunlight cooking the nucleus of the comet, now heading toward the sun, beyond its breaking point, they said.

 
The fragments of other comets, like Linear C, observed with the Hubble Space Telescope, survived only a few days. But 57P convoy could contain much sturdier parts.

The astronomers hope to study the fragments for at least several weeks as they move and evolve, which "should give us insight into the constitution and fragility of this comet and hopefully comets in general."

The comet consists of a main nucleus, to the far left in the horizontal image at the top of this story, and a train of companions from a few hundred to tens of meters of across, each identified by a different letter.

It will make its closest approach to the sun on July 31, at roughly the same distance as the orbit of Mars.

The string of pearls is about 620,000 miles (1 million kilometers) long. From our perspective on Earth, it would extend about the same distance in the sky as the moon's diameter. But 57P is much too faint to see with the naked eye.

Jewitt and colleagues Yanga Fernandez and Scott Sheppard will keep an eye on it for as long as they can, using a 7.2-foot (2.2-meter) telescope on Mauna Kea, a volcano 13,800 feet high (4,200 meters) where thin, dry air and extremely dark skies provide ideal astronomical viewing

"We intend to watch the fragments as they fade away from the heat of the sun. Eventually, we hope we'll see tiny dead remnants of the fragments that are left after all the ices have gone," Jewitt said.

"Of course, it's also possible that the fragments will completely disintegrate into dust, in which case nothing observable will be left."

Comets are primordial souvenirs of the early solar system. Most reside in thin packs beyond the planets, but some make periodic trips into the inner solar system.

下图为夏威夷大学2.2米口径望远镜观测到的该彗星，字母标识了该彗星部分碎块。

57P/du Toit-Neujmin-Delporte 得泰-纽敏-德伯特彗星
07月12日：亮度+15.77等，彗头直径7秒，凝结度3/9。

今天下午回到广州之后，一定给大家更多详细资料。