ESO100623：VLT发现了系外行星上的首个超级风暴

http://www.eso.org/public/news/eso1026/

eso1026 - Science Release  
23 June 2010
ESO公开报告2010年度第26#报告，科学类，2010.6.23即时公布。
VLT Detects First Superstorm on Exoplanet
VLT发现了系外行星上的首个超级风暴

                               
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Astronomers have measured a superstorm for the first time in the atmosphere of an exoplanet, the well-studied “hot Jupiter” HD209458b. The very high-precision observations of carbon monoxide gas show that it is streaming at enormous speed from the extremely hot day side to the cooler night side of the planet. The observations also allow another exciting “first” — measuring the orbital speed of the exoplanet itself, providing a direct determination of its mass.
天文学家首次在著名的系外行星——热木星HD 209458b上确认了一个超级风暴。高精度观测表明，在行星的永久白昼面上，灼热的一氧化碳（CO）气体以极高的速度涌向其永久黑暗面。观测还创了另一项“第一”：准确测出了行星的公转速度，从而能计算出其质量值。

http://www.eso.org/public/archives/images/original/eso1026a.tif, 4000 X 2827, 17.4MB

                               
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The results appear this week in the journal Nature.
本研究报告刊登在本周出版的《自然》期刊上。
“HD209458b is definitely not a place for the faint-hearted. By studying the poisonous carbon monoxide gas with great accuracy we found evidence for a super wind, blowing at a speed of 5000 to 10 000 km per hour‚” says Ignas Snellen, who led the team of astronomers.
天文学家团队领队 Ignas Snellen说：“HD 209458b上绝非善地。通过对其表面剧毒的CO气体运动的高，精度观测，我们确认了一个超级风暴，时速高达5000~1万km。”
HD209458b is an exoplanet of about 60% the mass of Jupiter orbiting a solar-like star located 150 light-years from Earth towards the constellation of Pegasus (the Winged Horse). Circling at a distance of only one twentieth the Sun–Earth distance, the planet is heated intensely by its parent star, and has a surface temperature of about 1000 degrees Celsius on the hot side. But as the planet always has the same side to its star, one side is very hot, while the other is much cooler. “On Earth, big temperature differences inevitably lead to fierce winds, and as our new measurements reveal, the situation is no different on HD209458b,” says team member Simon Albrecht.
HD 209458位于飞马座，离地球约150光年，是颗类太阳恒星。其行星HD 209458b，质量约为木星的60%，轨道长轴不到1/20天文单位，因此行星表面被主恒星强烈加热到1000℃以上。由于行星已经被恒星潮汐锁定，其一面永久朝向主恒星，因此两面的温差极大。团队成员西蒙.亚伯雷希解释道：”在地球上，巨大的温差必然导致暴风，此点在HD 209458b也雷同。“
HD209458b was the first exoplanet to be found transiting: every 3.5 days the planet moves in front of its host star, blocking a small portion of the starlight during a three-hour period. During such an event a tiny fraction of the starlight filters through the planet’s atmosphere, leaving an imprint. A team of astronomers from the Leiden University, the Netherlands Institute for Space Research (SRON), and MIT in the United States, have used ESO’s Very Large Telescope and its powerful CRIRES spectrograph to detect and analyse these faint fingerprints, observing the planet for about five hours, as it passed in front of its star. “CRIRES is the only instrument in the world that can deliver spectra that are sharp enough to determine the position of the carbon monoxide lines at a precision of 1 part in 100 000,” says another team member Remco de Kok. “This high precision allows us to measure the velocity of the carbon monoxide gas for the first time using the Doppler effect.”
HD 209458b是通过凌日法发现的第一个系外行星，它绕转周期仅3.5天，凌日时会产生3小时左右的遮光现象。在此期间，一小部分的恒星光芒将透过行星的大气层，并产生吸收现象。来自荷兰太空探索研究院（SRON）、莱顿大学和美国麻省理工学院（MIT）的团队，使用ESO甚大望远镜（VLT）上强大的冷冻红外中阶度光栅摄谱仪（CRIRES）探测、分析这些细微的特征谱线。在凌日阶段，累计观测时间约5小时。团队成员Remco de Kok说：”CRIRES是唯一能够把CO谱线位置的精度分辨率做到10万分之一的光谱仪。借助如此高的分辨率，我们首次测量了CO气体移动时的多普勒效应。“
The astronomers achieved several other firsts. They directly measured the velocity of the exoplanet as it orbits its home star. “In general, the mass of an exoplanet is determined by measuring the wobble of the star and assuming a mass for the star, according to theory. Here, we have been able to measure the motion of the planet as well, and thus determine both the mass of the star and of the planet,” says co-author Ernst de Mooij.
团队还砍获数个“第一”：他们准确测出了行星的公转速度。报告的联合作者 Ernst de Mooij说：”计算系外行星质量的一般方法是：测量主恒星的径向移动速度，然后推断造成此移动的系外行星质量。本次观测中我们还精确获得了行星的公转速度，这样就能计算出恒星和行星两者的质量值。“
Also for the first time, the astronomers measured how much carbon is present in the atmosphere of this planet. “It seems that H209458b is actually as carbon-rich as Jupiter and Saturn. This could indicate that it was formed in the same way,” says Snellen. “In the future, astronomers may be able to use this type of observation to study the atmospheres of Earth-like planets, to determine whether life also exists elsewhere in the Universe.”
另外，团队还首次测量出了HD 209458b大气中的碳含量。Snellen总结道：”看上去，这颗行星是富含碳的，与木星、土星类似。这表明它们形成于类似的环境。未来，天文上家可以采用我们的方法去分析类地行星的大气组成，并发现宇宙中其他的生命形式。“

More information

This research was presented in a paper that appears this week in the journal Nature: “The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b”, by I. Snellen et al.
本研究报告刊登在本周出版的《自然》期刊上，标题：“ HD209458b的轨道速度、绝对质量和超高速风暴”，作者：I. Snellen等。
The team is composed of Ignas A. G. Snellen and Ernst J. W. de Mooij, (Leiden Observatory, The Netherlands), Remco J. de Kok (SRON, Utrecht, The Netherlands), and Simon Albrecht (Massachusetts Institute of Technology, USA).
团队成员：荷兰莱顿大学  Ignas A. G. Snellen、Ernst J. W. de Mooij；
荷兰 Utrecht市，荷兰太空探索研究院（SRON） Remco J. de Kok；
美国麻省理工学院（MIT） Simon Albrecht。

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
ESO,欧洲南方天文台的缩写，欧洲最著名的政 府间合作的天文组织，由14个国家出资组成：澳大利亚、比利时、捷克共和国、丹麦、法国、芬兰、德国、意大利、荷兰、葡萄牙、西班牙、瑞典、瑞士和英国。 ESO致力于一项雄心勃勃的计划：设计、建造和操作强大的地面望远镜群，使天文学家观测宇宙、做出重大科学发现。ESO同时在推动、组织天文合作研究中扮演带头人角色。在智利北部阿塔卡马沙漠区域，ESO运作三个独特的、世界级的天文台：拉斯拉、帕拉纳尔和查南托天文台，ESO运作的甚大望远镜（VLT），是世界上最先进的可见光天文望远镜群；而VISTA是全球最大的巡天望远镜。欧洲各伙伴共有的革命性天文台——ESO的ALMA，是当今最大的射电望远镜项目。ESO眼下正计划一个42米口径的欧洲极大可见光/近红外望远镜项目，缩写为E-ELT，将成为全球最大的巡天眼。

                               
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Links  链接

* Research paper
相关专业PDF：http://www.eso.org/public/archives/releases/sciencepapers/eso1026/eso1026.pdf
* More info: Exoplanet Media kit PDF (in English and en Español)
系外行星的相关多媒体介绍：http://www.eso.org/public/outreach/products/press-kits/pdf/exoplanet_lowres.pdf

Contacts
相关联系人
Ignas Snellen
Leiden Observatory
Leiden, The Netherlands
荷兰莱顿市，莱顿天文台
Tel: +31 63 00 31 983
Email: snellen@strw.leidenuniv.nl

Henri Boffin
ESO, La Silla, Paranal and E-ELT Press Officer
Garching, Germany
德国加尔兴市，ESO拉斯拉、帕拉纳尔、E-ELT望远镜新闻办公室
Tel: +49 89 3200 6222
Cell: +49 174 515 43 24
Email: hboffin@eso.org

http://www.eso.org/public/videos/eso1026a/

Planet with superstorm (artist's impression)
行星上的超级风暴

http://www.eso.org/public/archives/videos/hd_and_apple/eso1026a.m4v , 18.0MB

http://www.eso.org/public/archives/videos/broadcast_sd/eso1026a.mov，32.9MB

本视频信息量不大，效果一般，是否下载大家自己选择吧。——gohomeman1注

Credit: ESO/L. Calçada
版权：ESO，制作者

PDF中，有好几个插图，但科学性比较强，有兴趣的去读一下吧。比如附图就是对CO、H2O、CH4的多普勒位移谱线模拟

the mass of the star is determined to be M1 = 1.00 ± 0.22 Msun, the mass of the planet to be M2 = 0.64 ± 0.09 Mjup at an orbital distance of a = 0.045 ± 0.003 AU (all 1σ uncertainties). It is encouraging to know that the different estimates of the mass of the host star from spectral modelling, such as M1=1.14 ± 0.10 Msun, and M1=1.06 ± 0.10 Msun, are fully consistent with this.

我们观测结果是：主星质量为1.00 ± 0.22太阳质量，行星质量为0.64 ± 0.09个木星，轨道距离为0.045 ± 0.003天文单位（所有数据的标准误差为1σ）。这与其他的光谱观测数据相合，比如1.14 ± 0.10、1.06 ± 0.10太阳质量。（另外的2个观测来源就不给出了，但我怎么看到VLT的测量误差更大得多呢？——gohomeman1注）

很有学术价值的发现，谢谢

HD 209458b 是一颗很早就被研究的系外行星。这些行星使我们发现：原来其他恒星系与我们的太阳系是大大的不同啊！有关哈勃、Spitzer对其的观测，看这个专题帖：
http://www.astronomy.com.cn/bbs/thread-140758-1-1.html