1、Exocomets may beas common as exoplanets系外彗星也许和系外行星一样常见Published: Monday, January 7, 2013 - 16:35in Astronomy & Space发表时间：2013 年 1月 7日，星期一 -16:35 于天文学与太空版块Comets can be seenin this artistic depiction of the young star Beta Pictoris as seen from theouter edge of its disk.NASA image byLynette Cook.彗星可以
2、在这一幅绘架座 星的年轻恒星艺术画的尘埃盘外边缘看到。美国宇航局丽奈特库克供图Comets trailingwispy tails across the night sky are a beautiful byproduct of our solarsystems formation, icy leftovers from 4.6 billion years ago when the planetscoalesced from rocky rubble. The discovery by astronomers at the University ofCalifornia, Berkeley,
3、 and Clarion University in Pennsylvania of six likelycomets around distant stars suggests that comets - dubbed“exocomets“ - are just as common in other stellar systems withplanets. 彗星拖着的划破夜空的纤细尾巴，是一个我们的太阳系形成的美丽的副产品，来自 46亿年前行星由岩石瓦砾合并而成时的冰冷遗留物。由加利福尼亚大学伯克利分校和位于宾夕法尼亚州的克莱瑞恩大学的天文学家发现的 6颗围绕遥远恒星的疑似彗星表明确实是彗星
4、被称为“系外彗星”就像在其他恒星系统的行星一样常见。Though only one ofthe 10 stars now thought to harbor comets is known to harbor planets, the factthat all these stars have massive surrounding disks of gas and dust a signature of exoplanets - makes ithighly likely they all do, said Barry Welsh, a research astronomer at UCBe
5、rkeleys Space Sciences Laboratory. 虽然已知包含有行星的 10颗恒星中只有 1颗现在认为包含有彗星，实际上所有这些恒星周围有大量的气体和尘埃系外行星的标志使它们极有可能都有彗星，巴里威尔士说，一名加州大学伯克利分校太空科学实验室的研究天文学家。“This is sortof the missing link in current planetary formation studies,“ Welsh said.“We see dust disks - presumably the primordial planet-forming material -arou
6、nd a whole load of stars, and we see planets, but we dont see much of thestuff in between: the asteroid-like planetesimals and the comets. Now, I thinkwe have nailed it. These exocomets are more common and easier to detect thanpeople previously thought.“ “在目前的行星形成的研究中，这是种缺失的环节， ”威尔士说。 ”我们看到的尘埃盘大概是最原
7、始的行星形成物质围绕在恒星周围塞满了轨道，并且我们看到了行星，但我们没有看到这些填充物之间更多的东西：类小行星的星子和彗星。现在，我想我们已经锁定它了。这些系外彗星较为常见，而且比人们以前认为的更容易探测到。 ”Welsh will presentthe findings on Monday, Jan. 7, during a meeting of the American AstronomicalSociety in Long Beach, Calif. Three of the new exocomets were reported in theOct. 2012 issue of the
8、 journal Publications of the Astronomical Society of thePacific by Welsh and colleague Sharon L. Montgomery of the Department ofPhysics at Clarion University. 威尔士将目前的调查结果于 1月 7日星期一在加利福尼亚州长滩举行的美国天文学会年会上发表，新的系外彗星中的 3颗由威尔士和克莱瑞恩大学物理学系的同事沙伦L蒙哥马利在 2012年 10月期的太平洋天文学会杂志刊物上做了报告。Welsh also willparticipate in
9、a media briefing on Tuesday, Jan. 8, at 2:30 p.m. PST in Room204 on Level 2 of the Long Beach Convention Center. 威尔士还将于太平洋标准时间 1月 8日星期二下午 2 : 30参加一个在长滩会议中心 2楼204房间举行的媒体新闻发布会。Welsh summarizedthe current theory of planet formation as “interstellar dust under theinfluence of gravity becomes blobs, and
10、the blobs grow into rocks, the rockscoalesce and become bigger things - planetesimals and comets - and finally,you get planets.“ 威尔士总结目前的行星形成理论为“星际尘埃在引力的影响下变成团块，然后团块成长为岩石，岩石的凝聚成为更大的东西星子和彗星最后，你得到了行星。 ”Many stars areknown to be surrounded by disks of gas and dust, and one of the closest,beta-Pictoris
11、(-Pic), was reported to have comets in 1987. In 2009,astronomers found a large planet around -Pic about 10 times larger thanJupiter. Three other stars - one discovered by Welsh in 1998 - were subsequentlyfound to have comets.众所周知许多恒星被周围的气体和尘埃环绕，而其中一个最接近的，绘架座贝塔星（-Pic） ，1987 年据报道有彗星。2009 年，天文学家发现了一颗大行
12、星围绕绘架座 星旋转大约是木星的 10倍大。其他 3颗恒星其中一个发现于 1998年后来发现有彗星。“But then,people just lost interest. They decided that exocomets were a done deal, andeverybody switched to the more exciting thing, exoplanets,“ Welsh said.“But I came back to it last year and thought, Four exocomets is not allthat many compared to
13、the couple of thousand exoplanets known - perhaps I canimprove on that.“但是之后，人们就失去了兴趣。他们决定系外彗星是一件木已成舟的事情，每个人都转向了更令人兴奋的事情系外行星， ”威尔士说。 ”但我去年又回来关注它并且认为， “4颗系外彗星不是一切，许多可以和那几千颗已知的系外行星相比或许我可以改进。 ”Detecting cometsmay sound difficult - after all, the snowballs are typically only 5-20kilometers (3-13 miles)
14、in diameter. But Welsh said that once comets areknocked out of their parking orbit in the outer reaches of a stellar system andfall toward a star, they heat up and evaporate. The evaporating comet, which iswhat we see with comets such as Halley and next years highly anticipated CometISON, creates a
15、brief, telltale absorption line in the spectrum of a star. 探测彗星听起来很难毕竟，这些雪球通常只有 5-20公里（3 - 13 英里）直径。但是，威尔士说一旦彗星被从它们的泊车轨道淘汰到达一个恒星系统的外层并向着恒星下降，它们发热并挥发。挥发的彗星，就是是我们所看见的彗星比如哈雷彗星和明年高度期待的彗星 ISON，创造了一个简短的、泄露秘密的恒星光谱吸收线。The six newexocomet systems were discovered during three five-night-long observing runsbet
16、ween May 2010 and November 2012 using the 2.1-meter telescope of theMcDonald Observatory in Texas. The telescopes high resolution spectrographrevealed weak absorption features that were found to vary from night to night,an outcome that Welsh and Montgomery attributed to large clouds of gasemanating
17、from the nuclei of comets as they neared their central stars.这 6颗新的系外彗星系统被发现于运行于 2010年 5月和 2012年 11月之间的 3次五夜长观测，使用德克萨斯麦克唐纳天文台的望远镜 2.1米望远镜。该望远镜的高分辨率光谱仪显示弱吸收的特点，每晚在不同位置发现，结果当他们接近其中央恒星时，威尔士和蒙哥马利归因于彗核所产生的大型气体云。All of the newlydiscovered exocomets - 49 Ceti (HD 9672), 5 Vulpeculae (HD 182919), 2Andromeda
18、e, HD 21620, HD 42111 and HD 110411 are around very young type Astars, which are about 5 million years old, because Welshs detection techniqueworks best with them. With a higher resolution spectrograph, he might be ableto detect comets around the older and yellower G and F stars around which mostexo
19、planets have been found. 所有新发现的系外彗星鲸鱼座 49（HD 9672） ，狐狸座 5（HD182919） ，仙女座2，HD21620，HD42111 和 HD110411环绕非常年轻的 A类恒星，年纪大约是 500万岁，因为威尔士关于它们的检测技术运转最佳。应用高分辨率摄谱仪，他也许能发现彗星环绕更老和更黄的 G和 F恒星，同时也被大多数发现的系外行星环绕。Nevertheless, allevidence suggests that these dusty A stars should have planets, and planets arethe only
20、thing that could knock a comet out of its orbit and make it falltoward its star. 然而，所有证据表明，这些布满尘埃的 A类恒星应该拥有行星，行星是唯一能把彗星挤出轨道使它落向恒星的物体。“If itquacks, waddles and has feathers, then its probably a duck,“ he said.“如果它嘎嘎叫，蹒跚而行并有羽毛，那么它可能是一只鸭子， ”他说。The work wassupported by the National Aeronautics and Space Administration.
