航空航天港

 找回密码
 注册会员

QQ登录

只需一步,快速开始

查看: 14403|回复: 123
收起左侧

系外行星/类地行星新发现跟踪:重要成果!70%恒星有行星,其中1/5有类地行星

[复制链接]
hkhtg090201 发表于 2009-10-20 13:34 | 显示全部楼层 |阅读模式

对本站感兴趣的话,马上注册成为会员吧,我们将为你提供更专业的资讯和服务,欢迎您的加入!

您需要 登录 才可以下载或查看,没有帐号?注册会员

x
本帖最后由 hkhtg090201 于 2016-8-15 15:20 编辑


++2016-08-14  标题加入"/类地行星"关键词.

=====================

欧洲天文学家宣布新发现32颗系外行星(图)2009年10月20日 10:04  新浪科技

 新浪科技讯 北京时间10月20日消息,据国外媒体报道,欧洲天文学家日前宣布在太阳系外新发现了32颗行星,这意味着系外行星总数已超过400颗。
  据研究人员介绍,这32颗系外行星大小不等,有的质量仅是地球的5倍,有的质量是木星的5到10倍。天文学家通过设在智利拉斯拉的欧洲南方天文台3.6米望远镜上的超敏感观测仪发现了这些系外行星的踪迹。此次发现令天文学家们激动不已,因为这表明银河系内可能存在大量的低质量行星。
  瑞士日内瓦大学天文学家斯蒂芬·乌德里(Stephane Udry)说:“根据最新研究结果,我们现在确定了一个问题,即至少40%的类日恒星具有低质量的行星。这一发现确实很重要,因为意味着低质量的行星基本上无处不在。一个令人非常感兴趣的事实是,电脑模型会对它们的特点做出预测,我们也会找到它们。此外,电脑模型甚至还能预测像地球一样质量更低的行星。”
  最新发现使得已知系外行星的数量超过400颗。之前的系外行星都是通过一系列天文技术和望远镜确认的,而最新一批则是欧洲南方天文台高精度视向速度行星搜索器(HARPS)观测的结果。高精度视向速度行星搜索器利用了一种有时被称为“摇摆法”(wobble technique)的技术。这是一种间接的观测方法,即通过行星在经过恒星时所引起的摇摆现象,预知系外行星的存在。
  天文学正逐步突破当前探测系外行星技术的限制,迄今发现的大多数系外行星都是类似木星质量,或是比木星质量更大的天体。但是,高精度视向速度行星搜索器将重点聚焦于温度相对低的小恒星(所谓的M级恒星),希望发现低质量行星的踪迹。低质量行星的活动极有可能像太阳系中的岩质行星一样。
  在已知28颗质量低于20倍于地球质量的系外行星中,高精度视向速度行星搜索器现已确认了其中的24颗,而剩余6颗就在最新发现的列表中。乌德里教授在接受英国广播公司采访时说:“我们在5倍于地球质量的天体上有两个候选,在6倍于地球质量的天体上也有两个候选。”
  今年4月,天文学家宣布高精度视向速度行星搜索器发现了一个质量仅是地球两倍的行星。科学家认为这颗行星上没有生命存在,因为它距其母恒星非常近,表面温度高的惊人。高精度视向速度行星搜索器任务小组在10月19日宣布了最新发现的32颗系外行星。他们同时表示,希望在未来6个月里证实另一批相同数量的系外行星的存在。
  天文学家的最终目标是在恒星的“适居带”发现岩质行星。所谓恒星“适居带”是指一个温度在支持液态水存在范围内的轨道。科学家认为,引入更新、更敏感的观测技术可以让他们在未来几年内确认此类天体。
  美宇航局在今年初发射了“开普勒”天文望远镜,希望通过观测恒星穿越地球大小的行星时光线的微妙变化,确定此类行星的踪迹。若要正确识别行星的特点,便需要不同的观测方法。开普勒“飞越法”可以揭示天体的直径,而类似高精度视向速度行星搜索器这样的测量仪器则能揭开此类天体的质量之谜。(孝文)

http://planetquest.jpl.nasa.gov
snowtiger 发表于 2009-10-20 16:48 | 显示全部楼层
这是一种间接的观测方法,即通过行星在经过恒星时所引起的摇摆现象,预知系外行星的存在。
------------
这话有逻辑问题。在预知那里有行星之前怎么能观察摇摆啊。估计是观察恒星摇摆吧。。。。。
 楼主| hkhtg090201 发表于 2009-10-21 07:03 | 显示全部楼层
我想,就应该是恒星的摇摆。
 楼主| hkhtg090201 发表于 2009-10-27 20:56 | 显示全部楼层
为太阳系外行星起名
2009年10月26日 18时15分 星期一      

自1995年以来,天文学家已经发现了超过400颗太阳系外行星。然而没有一颗行星有正式的名称,它们都只有一个科学编号,如MOA-2008-BLG-310-Lb。国际天文学会拒绝起名的官方理由是:天文学家预计将会发现无数颗地外行星,给它们都起上名字是完全不可行的事。
德国Max Planck学院的Wladimir Lyra认为,这种立场是没有意义的。恒星很普遍,给它们的每颗行星都赋予名字是不切实际的,但这不妨碍给其中一些行星命名。因为在无数颗太阳系外行星中,有一些肯定将在天文学历史留下重要的痕迹,它们或能帮助人类理解行星的性质,或许存在生命可让人类了解生命的演化。Lyra提出了一套命名规则,使用希腊和罗马神话中的名字,和天空中的星座命名方法类似。他给目前发现的403行星都赠送了一个名字,如CoRoT-3b叫克拉托斯(Cratos),WASP-6b叫透克尔(Teucrus),HD 132406b叫阿特拉斯(Atlas)。完整名单见预印本。
 楼主| hkhtg090201 发表于 2009-12-17 15:35 | 显示全部楼层
40光年外发现水行星 仅1/4表面为岩石
2009年12月17日 09:30  新浪科技

天文学家发现一颗绕昏暗恒星运转的类地行星,距地球仅40光年。它是一个热气腾腾的“水世界”

天文学家认为这颗行星与此前在太阳系外发现的任何系外行星相比更接近地球。
  新浪科技讯 北京时间12月17日消息,据英国《每日邮报》报道,天文学家发现一颗绕昏暗恒星运转的类地行星,距地球仅40光年。它是一个热气腾腾的“水世界”,体积是地球的6倍。据信,这颗行星75%的表面区域被水覆盖,但由于温度太高,它无法支持地球型生命存在。有证据显示,这个“水世界”同样拥有大气层。天文学家认为这颗行星与此前在太阳系外发现的任何系外行星相比更接近地球。

  这颗有水行星被归入“超级地球”行列,体积在地球等体积较小多岩行星和天王星、海王星等冰巨星之间。虽然它的母星是一颗昏暗的红矮星,亮度只有太阳的三千分之一,但由于二者之间距离太近,这颗有水行星的表面温度高达200摄氏度。有水行星与母星之间的距离仅为130万英里(约合209万公里),绕母星轨道运行一周只需要38小时。

  这颗绕红矮星GJ1214运行的行星是一个小型地面望远镜阵列发现的,所使用的望远镜并不比很多业余爱好者的大。MEarth Project计划利用8架同样的直径16英寸(约合40厘米)望远镜监视2000颗红矮星。红矮星是银河系最常见的恒星类型。望远镜通过观测红矮星亮度变化,证明一颗行星在其前方穿过。由于太过昏暗,红矮星本身也提高了这种方式发现行星的可能性。

  通过测算行星穿过导致的亮度降低,科学家能够计算出一颗行星的密度并对其成分进行有根据的猜测。新发现的行星被命名为“GJ1214b”,据信表面四分之三区域被水和冰覆盖,留给岩石的区域只有四分之一左右。

  哈佛-史密森尼中心研究生、天文学家查克里·伯塔发现了这颗有水行星。他表示:“尽管温度很高,但它仍旧是一个有水世界。与其它任何已知系外行星相比,这颗行星体积更小,温度更低并且与地球更为接近。”

  科学家认为除了GJ1214b地表之外,一些东西一定阻隔来自母星的光线,它的周围可能是一个由氢和氦构成的大气层。借助于哈勃太空望远镜,天文学家可能确定这颗行星的成分。MEarth Project负责人大卫·查博内欧表示:“由于这颗行星与地球非常接近,‘哈勃’应该可以对大气层进行探测并确定其构成。幸运的话,它将成为第一个拥有已证实大气层的超级地球,虽然这个大气层可能对我们已知的生命并不友好。”

  16日出版的《自然》杂志报道了这一发现。在刊登于《自然》的一篇文章中,著名行星猎人、美国加利福尼亚州大学杰弗里·马西教授对这个水世界可能呈现的景象进行了猜测。他写道:“它可能拥有深度极高的海洋,应该呈液态。由于母星赋予的热量,其表面温度达到190摄氏度左右。此外,一个类似桑拿浴的蒸汽大气层也可能存在。”(孝文)
原文:
http://tech.sina.com.cn/d/2009-12-17/09303685853.shtml
 楼主| hkhtg090201 发表于 2010-1-8 09:21 | 显示全部楼层
第二个超级地球被发现     .. the second smallest exoplanet...super-Earths.


发现者: 外行星猎人..凯克-- Planet hunters using ....Keck/HIRES
  
行星介绍:..被命名为HD 156668b?
      1.大小:体积是地球的4倍....four times the mass of Earth
      2.温度:?
    3.所属恒星:..It orbits its host star (HD 156668) every 4.6 days..
      4.距离:..80 light years from Earth

更多:
http://spacefellowship.com/news/ ... xoplanet-found.html
 楼主| hkhtg090201 发表于 2010-1-10 15:22 | 显示全部楼层
《阿凡达》科学表现打分 潘多拉是颗行星吗

2010年01月10日 09:49:57  来源:新京报  

    《阿凡达》是电影技术的里程碑。卡梅隆堪称工程技术专家,据说为了制作《阿凡达》,他还请来了植物学家、天体物理学家、音乐教授和考古专家分别设计了片中潘多拉星球的植物、大气密度以及一种三声阶的异族音乐。《阿凡达》是卡梅隆同学的一份艺术课作业,但号称里面有很多科学内容。那如果一个科学老师审查这份作业,会给它怎样的评语呢?认真算起来,或许未必能及格。

    【大课题】

    “潘多拉”是颗行星吗?

    电影《阿凡达》的故事发生在一个名叫“潘多拉”的星球。它是“半人马座阿尔法A星”(Alpha Centauri A)的一颗行星气态行星“独眼巨人”(Polyphemus)的卫星。潘多拉星球是一个气候相当温暖的星球,但它的质量比地球小,所以上面的重力也小,生物可以长得非常巨大。它的空气有毒,人类不能呼吸。

    计算轨道很困难

    现实中,确实存在“半人马座阿尔法A星”。它距离地球4.37光年,它是除太阳外离地球最近的恒星之一。为什么叫“A星”呢,原来半人马座阿尔法星是一个三星系统,有3颗恒星互相绕转,又作为一个整体绕着银河系中心运动。

    2008年1月,一个由天文学家费舍尔(Debra Fischer)领导的小组开始通过智利的CTIO1.5米直径望远镜考察半人马座阿尔法星,这项研究将要持续5年。她的小组想要通过这颗恒星有规律的光线变化来推断环绕它周围运转的天体。这种技术已经被用来推断出半人马座阿尔法星有像木星那么大的行星绕着它旋转。费舍尔说:“那里很有可能存在像地球那样的行星。”

    因为同时受到三颗恒星的影响,行星的运动可能会很诡异。三星中A星和B星的运动接近于绕着一个共同中心旋转,两者之间的距离在11个天文单位和36个天文单位之间(天文单位是地球和太阳之间的距离),所以想象它们的行星怎么运动还真是费神。半人马座第三颗星是一颗红矮星,叫“比邻星”和A、B两颗星组成的系统相互绕转,它距离A、B两星较远,对它们的行星影响不大。如果A星和B星组成的系统真的有行星,那么经过计算,如果它们和其中一颗恒星的距离超过2个天文单位,那么在共同引力的作用下,行星可能会被“甩”出系统,跌入茫茫宇宙之中。

---------------------

太阳系外卫星尚未发现

    “好消息”是,经过计算,在这个系统里还是存在生命的“黄金地带”的,在那里不太冷也不太热,可以有大量液态水存在。A星比太阳大一些,在1.2个天文单位处是“黄金地带”;而B星有太阳的90%大,在0.75个天文单位处是“黄金地带”。而且两颗星的化学成份和太阳类似,它们的行星的元素组成可能也会类似地球,有可能形成早期地球上面的那种“原始生命汤”。现在仍然没有确切的结论说半人马座阿尔法星到底有没有地球大小的行星,但是费舍尔表示,2012年左右就能得出结果。

    片中的行星“独眼巨人”是编剧虚构的,它的卫星更是一种幻想。实际上,现在还没有天文学家发现太阳系外的卫星,但他们预测早晚有一天会发现。人马座阿尔法星是一个值得一看的地方。事实上,韦伯望远镜可能很快就能看到太阳系外的“月亮”,并且可以探测它们是否有氧气、水蒸气这些地球生命形式所需的基本要素。

  存在生命难度很大

    虽然“潘多拉”在理论上有可能存在,但生命要在上面生存还是有问题。虽然这些气体行星的卫星可以得到恒星足够的光照,但它们的“主子”行星可能会对它们上面的生命造成很大威胁。它穿过行星磁极的时候,肯定会被很多离子轰击。因为行星巨大的引力,可能会引起很大的潮汐和火山爆发。想想看,像《2012》里那样的大场面每年都出现,让陆上生物怎么活?

    还有个问题,潘多拉星的重力比地球小,它的空气应当比地球稀薄,那么这样的空气是如何提供巨大生物呼吸的需要,又如何能让巨大飞龙腾空的呢?只有一种可能,组成潘多拉星大气的主要成份比地球空气重。制片方说,这颗星的大气由甲烷、氨气和氯气等组成。这三种气体中只有氯气比空气重,氯气本身有毒,它和水蒸气结合,会在空气中形成大量的盐酸。看来,潘多拉星球还真够可怕的。

---------------------
 楼主| hkhtg090201 发表于 2010-7-2 17:04 | 显示全部楼层
地面望远镜首次拍到系外行星:质量为木星8倍

2010年07月02日 07:41  新浪科技



绕类日恒星运转的系外行星的首张照片

  新浪科技讯 北京时间7月2日消息,据美国太空网报道,加拿大天文学家表示,在太阳系外发现的一颗行星已被正式确认为绕类日恒星运转的系外行星,同时,它也是迄今由地面望远镜直接拍到的第一颗系外行星。

  为日地距离300倍

  这颗系外行星的质量是木星的8倍,以异乎寻常的距离(是日地距离的300倍)绕主恒星运转。2008年,天文学家利用地面望远镜的可见光观测仪器最早发现了它,这也是地面望远镜首次直接拍到系外行星的照片。不过,当时还存在一种可能性,即由于物体、恒星和观测者的幸运排列,从地面的视角观测,它正在绕其恒星运转。

  天文学家戴维-拉弗伦尼尔(David Lafreniere)说:“我们的最新观测结果排除了这种排列的可能性,由此证实这颗行星和恒星之间存在关联。”拉弗伦尼尔领导的研究小组发现了这颗系外行星。天文学家利用双子星天文台的高清晰适应性光学技术,进行了新一轮观测,最终证实该行星绕其主恒星旋转。双子星天文台是一个多国合作项目,由架设在夏威夷莫纳克亚和智利塞罗帕琼山山顶的8米双筒天文望远镜构成。

  主恒星的质量估计相当于太阳质量的85%,位于距离地球500光年远的一个区域内,该区域存在大量名为天蝎座上部组(Upper Scorpius Association)的年轻恒星,它们大概形成于500万年前。那颗系外行星的表面温度估计在2700华氏度(约合1500摄氏度)以上,远比木星的表面温度高。木星大气云顶温度约为华氏零下166度(约合摄氏零下110度)。

  据研究人员介绍,这个恒星系(太阳系的历史约为46亿年)相对年轻,解释了该系外行星温度奇高的原因。形成期间,在自身引力的作用下,该系外行星的收缩迅速令其温度升高至数千度。一旦这个收缩期结束,它通过向四周释放红外光令温度缓慢下降。数十亿年以后,这颗行星的表面温度将最终达到与木星一样的水平。

  对传统理论提出挑战

  拉弗伦尼尔及其研究小组最早于2008年9月宣布了他们的研究发现。当时,他供职于加拿大多伦多大学,如今则在蒙特利尔大学和魁北克天体物理学研究中心任职。2008年,研究人员宣称,这是围绕类日恒星轨道运转的系外行星的首张照片。其他天文学家也曾表示有过类似的发现,包括2004年发现的像是行星的天体或名为棕矮星的类恒星天体。

  拉弗伦尼尔说:“2008年的时候,我们确切了解到,有一个质量如年轻行星的天体在天空中紧挨着一颗年轻的类日恒星。”两个天体距离如此之近似乎表明,它们彼此之间存在着密切联系,但是,还有一种可能性,即它们之间没有任何关联,只是偶然在天空呈现如此近的排列。其中一个天体可能距离另一个天体非常远或非常近。

  所以,要证实天文学家的结论,还需要进一步观测。研究结果将刊登在最新一期的《天体物理学杂志》上。这个名为1RXS J160929.1-210524(简称1RXS 1609)的恒星系让科学家有了从事研究的独特例证,因为其与恒星的极端距离似乎对传统行星形成理论提出挑战。

  参与最新研究的多伦多大学天文学家雷-贾亚瓦哈纳(Ray Jayawardhana)说:“这个外星世界不可能的位置或许告诉我们,行星形成方式并非只有一种。或者,它预示着新生行星的狂暴幼年时期,那个时候,它们之间的亲密接触会将周围新生行星拖拽到腹地。”

  采用最新光学观测手段

  拉弗伦尼尔的研究小组最初在2008年4月利用双子星天文台发现了这颗系外行星,令其成为第一颗通过直接观测发现的已知绕类日恒星旋转的潜在行星。当时,研究人员捕捉了这颗行星的光谱,由此可以确定它的许多特性,这些特性在最新研究得到证实。拉弗伦尼尔说:“回首过去,这项发现使得我们的初始数据成为迄今得到证实的系外行星的第一个光谱。”光谱说明了这颗系外行星因大气中水蒸汽、一氧化碳、氢分子含量而形成的吸收特性。

  这不是利用直接成像手段发现的唯一一颗系外行星。自最初发现1RXS 1609以来,天文学家还发现了其他几个系外行星,其中包括围绕HR 8799恒星轨道运转的一个三行星系统。这项发现也是利用双子星天文台获得的。最新得到证实的系外行星十分独特,因为围绕HR 8799恒星轨道运转的系外行星距离其主恒星更近。

  对1RXS 1609恒星系的研究还证实,这个系统中没有更靠近主恒星的超大行星(质量是木星的1倍至8倍)了。进一步观测可能还会发现这些奇特、遥远行星的来历的证据。实际上,在未来几年内,由于它们之间的轨道变化,应该有可能发现这颗行星及其恒星运动的微小差异。但是,参与这项研究的多伦多大学天文学家马滕-范-柯克维吉克(Marten van Kerkwijk)说,这种差异会“非常小”,因为最快的轨道周期可能也超过一千年。

  通过双子星天文台,天文学家或许还能精确测量这颗系外行星相对于其主恒星的速度。这可以帮助天文学家确定该行星是正依照接近于圆形的轨道运行,还是正处于非圆形轨道或不受束缚的轨道运行。如果确实形成于距离主恒星很远的地方,那么就符合第一种情况,如果形成于距离主恒星更近的地方,只是由于与另一颗系外行星邂逅而被“踢走”,则符合第二种情况。

  双子星天文台的适应性光学系统对1RXS 1609恒星系的观测至关重要。拉弗伦尼尔说:“没有适应性光学系统,我们或许不能看到这颗行星。大气阻滞了观测恒星的视线,令其不断延续,看上去比周围的暗淡行星更明亮一些,使得我们难以观测到这颗行星。适应性光学技术消除了这种模糊景象,让我们可以更清楚地观测到距离恒星非常近的昏暗行星。” (秋凌)

本帖子中包含更多资源

您需要 登录 才可以下载或查看,没有帐号?注册会员

x
HaleBoppComet 发表于 2010-7-8 19:28 | 显示全部楼层
地面望远镜首次拍到系外行星:质量为木星8倍

2010年07月02日 07:41  新浪科技



绕类日恒星运转的系 ...
hkhtg090201 发表于 2010-7-2 17:04


相似于我们处在伽利略时代 我们用望远镜看到它 类似当年伽利略看到木星一样
 楼主| hkhtg090201 发表于 2010-7-17 08:31 | 显示全部楼层
NASA找到 ‘象彗星一样拖着尾巴’ 的超级热行星.

NASA Finds Super Hot Planet With Unique Comet-Like Tail

Published by Klaus Schmidt on Fri Jul 16, 2010 8:01 am via: NASA Share




NASA, exoplanet, Hubble, HD 209458bWASHINGTON — Astronomers using NASA’s Hubble Space Telescope have confirmed the existence of a baked object that could be called a “cometary planet.” The gas giant planet, named HD 209458b, is orbiting so close to its star that its heated atmosphere is escaping into space.

Observations taken with Hubble’s Cosmic Origins Spectrograph (COS) suggest powerful stellar winds are sweeping the cast-off atmospheric material behind the scorched planet and shaping it into a comet-like tail.


This artist's illustration shows a view of HD 209458b, as seen from the surface of a hypothetical nearby companion object.
“Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like,” said astronomer Jeffrey Linsky of the University of Colorado in Boulder, leader of the COS study. “We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. The most likely interpretation is that we have measured the velocity of material in a tail.”

The planet, located 153 light years from Earth, weighs slightly less than Jupiter but orbits 100 times closer to its star than the Jovian giant. The roasted planet zips around its star in a short 3.5 days. In contrast, our solar system’s fastest planet, Mercury, orbits the sun in 88 days. The extrasolar planet is one of the most intensely scrutinized, because it is the first of the few known alien worlds that can be seen passing in front of, or transiting, its star. Linsky and his team used COS to analyze the planet’s atmosphere during transiting events.
During a transit, astronomers study the structure and chemical makeup of a planet’s atmosphere by sampling the starlight that passes through it. The dip in starlight because of the planet’s passage, excluding the atmosphere, is very small, only about 1.5 percent. When the atmosphere is added, the dip jumps to 8 percent, indicating a bloated atmosphere.

COS detected the heavy elements carbon and silicon in the planet’s super-hot 2,000 degrees Fahrenheit atmosphere. This detection revealed the parent star is heating the entire atmosphere, dredging up the heavier elements and allowing them to escape the planet.

The COS data also showed the material leaving the planet was not all traveling at the same speed. “We found gas escaping at high velocities, with a large amount of this gas flowing toward us at 22,000 miles per hour,” Linsky said. “This large gas flow is likely gas swept up by the stellar wind to form the comet-like tail trailing the planet.”

Hubble’s newest spectrograph has the ability to probe a planet’s chemistry at ultraviolet wavelengths not accessible to ground-based telescopes. COS is proving to be an important instrument for probing the atmospheres of “hot Jupiters” like HD 209458b.

Another Hubble instrument, the Space Telescope Imaging Spectrograph (STIS), observed the planet in 2003. The STIS data showed an active, evaporating atmosphere, and a comet-tail-like structure was suggested as a possibility. But STIS wasn’t able to obtain the spectroscopic detail necessary to show a tail, or an Earthward-moving component of the gas, during transits. The tail was detected for the first time because of the unique combination of very high ultraviolet sensitivity and good spectral resolution provided by COS.

Although this extreme planet is being roasted by its star, it won’t be destroyed anytime soon. “It will take about a trillion years for the planet to evaporate,” Linsky said.

The results appeared in the July 10 issue of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute, operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, conducts Hubble science operations.

本帖子中包含更多资源

您需要 登录 才可以下载或查看,没有帐号?注册会员

x
 楼主| hkhtg090201 发表于 2010-7-26 11:40 | 显示全部楼层
五大类似太阳星系被发现 外星生命体或真的存在

2010年07月26日 10:47   来源: 科学网-kexue.com 卡卡西



    开普勒望远镜在近期发现了140颗类地行星的消息在天文界引起了巨大的轰动,紧跟而来的则是美国宇航局最新数据的公布,美国宇航局的官员表示,在庞杂的星系中,至少发现了5个类似于太阳系的星系。

    开普勒望远镜在近几周通过对太空的扫描发现了大量的类地行星,这使得美国宇航局感到非常的兴奋。对于它的杰出贡献,美国宇航局的官员也是进行了赞扬,认为它优越的性能将会在未来发挥更重要的作用。

    对于140颗类地行星的进一步观测还需要科学家们多加努力,美国宇航局的教授说道:“虽然详尽的工作还需要做,但开普勒望远镜所带来的意义却是非凡的,我们期待发现更多的类地行星,人类在宇宙中并不孤独。”

    此前科学网(kexue.com)也是报道了类地行星在近期呈现井喷,未来人类可能移居其他星球的消息。而美国宇航局的说法则证实了这一点,他们表示,在多达140颗类地行星的所在星系中,至少有5个星系与太阳系类似。这意味着他们产生生命的条件将更为成熟,尽管距离人类移居还需要很长的路要走,但这绝不意味着是无法实现的。

    一位负责开普勒探测器的研究人员说道:“下一步的工作重点是对行星的大气进行研究,看是否能找到生命的迹象。或许我们可以真的发现外星人。”而根据调查显示,在宇宙中可供人类居住的行星数量或在百万颗左右。

===================
PS:有可能被评为 2010年 十大 xxx 吧.
Everett 发表于 2010-7-27 13:39 | 显示全部楼层
KEPLER的任务就是很让人期待
发现一百多颗类地行星很正常,还得看这些行星在不在适宜居住带上
 楼主| hkhtg090201 发表于 2010-7-29 07:39 | 显示全部楼层
Kepler主管认为天文学家Sasselov的发言用词混乱,不应该用‘类地的’而应该是‘地球大小的’这个词,并且认为行星科学家的兴趣应该放在行星的结构上,而不是上面有没有生命上。

Kepler mission on the verge of more planet discoveries
BY STEPHEN CLARK...SPACEFLIGHT NOW
Posted: July 28, 2010


The Kepler space telescope has uncovered a treasure trove of candidate planets the size of Earth circling other stars, potentially reshaping scientists' view of the universe.


Artist's concept of Kepler. Credit: NASA


Dimitar Sasselov, an astronomer at Harvard University, presented the latest round of Kepler data at the TEDGlobal conference in the United Kingdom earlier this month.

One slide of Sasselov's presentation showed a breakdown of Kepler candidate planets, showing about 140 of the potential worlds are "like Earth."

"You can see here the small planets dominate the picture," Sasselov said.

Launched in March 2009, Kepler's sensitive camera stares at a field of stars in the constellations Cygnus and Lyra. The telescope looks for tiny dips in each star's brightness, a sign something is passing between the star and the Kepler spacecraft.

Sasselov noted the targets in his presentation were just candidates, but he said the data points to an exciting possibility.

"The statistical result is loud and clear," Sasselov said. "And the statistical result is that planet like our own Earth are out there. Our own Milky Way galaxy is rich in these kind of planets."

But don't pop the cork on the champagne yet.


NASA officials are rushing to define the meaning Sasselov's presentation.

"We're very happy that Kepler is making very precise measurements that allow us to identify planets as small as the Earth, although as yet, we have not talked about Earth-like orbits around sun-like stars," said Jon Morse, the director of NASA's astrophysics program. "I think some of the confusion out there is a matter of language and what people are interpreting."

William Borucki, Kepler's top scientist at the Ames Research Center, agreed that the confusion is a matter of Sasselov's choice of words.

"When an astrophysicist like Dimitar Sasselov talks about planets, he's interested in the structure of the planet," Borucki said. "He has no interest in whether there's life on it or not. That's not his business."

Media reports last week picked up Sasselov's announcement, concluding that Earths are scattered throughout the universe, potentially teeming with life.

"A lot of the misunderstanding occurred because he used the inappropriate term for talking to the public. He should not have said Earth-like. He should have said Earth-sized," Borucki said in an interview Tuesday.

There could be countless Earths scattered throughout the galaxy, but it's far too early for researchers to make any such announcement.

For one thing, Kepler is not equipped to search for life.

"The Kepler mission can measure the size of planets by the depth of the dip and the size of the star," Borucki said. "The one thing it cannot do is tell you whether the planet is Earth-like. People, when they think of Earth-like, they think of things like water, they think of reasonable temperatures and possible life. We can't do that. That's a future mission, I'm sure."


Kepler is staring at stars in the constellations Cygnus and Lyra. Credit: Carter Roberts


The telescope also is not yet able to find planets in the so-called habitable zone, a sweet spot just the right distance from a parent star.

Sasselov clarified his presentation in a blog posting Tuesday night on NASA's website.

"Indeed, Kepler has not discovered Earth-like planets in habitable zones. We have not found Earth-size planets; at this time we have found only planet candidates - 706 of them as of June 15, 2010, based on only 43 days of data with 306 released and discussed in a paper by the Kepler team," Sasselov wrote in the blog.

Kepler is currently only searching for planets with orbital periods of less than three months, so any new rocky worlds would reside far too close to the parent star to be habitable. Such planets could harbor oceans of lava.

The European Space Agency's COROT mission, another planet-hunting telescope, discovered the smallest extrasolar planet. When announced in February 2009, scientists said the COROT-7b planet is just 1.7 times the size of Earth, but it orbits hellishly close to its parent star.

Sasselov's 140 "Earth-like" planet candidates were estimated to be less than twice the size of Earth.

Borucki said Kepler scientists will expand their search for planets in the habitable zone once they finish writing an advanced software program to analyze stars over longer periods of time.

Kepler rotates on its axis every three months, meaning light from a specific star falls on a different set of CCDs inside the telescope's 95-megapixel camera.

"The different CCDs have different sensitivities, so it looks to us as if from three months to three months there's a big change in all the brightnesses of the stars," Borucki said.

A computer progarm has to stitch together observations from each three-month period to find planetary transits occurring at longer intervals.

"The computer program can't do that yet," Borucki said. So we can't find anything with significantly longer periods. We simply can't find things in the habitable zone until we finish the computer program. That's what we're working on."

Planets in more distant orbits would pass in front of the parent star at greater intervals. For example, an extraterrestial telescope in the faraway galaxy could only see Earth transit the sun once per year.

"We want to be able to say not only can we find small planets, but we can find small planets in long-period orbits, orbits that would be in the habitable zone," Borucki said.


Artist's concept of a planetary transit in front of a star. Credit: European Southern Observatory


The Kepler team's scientific prudence means it could be several years before NASA is prepared to make an Earth-shattering announcement.

"It takes an Earth a year to go around the sun, so if you're looking for an Earth-sized planet in an Earth-like orbit around a sun-like star, they want to see several transits before they can verify that it's a planet and not something else," Morse said.

Once Kepler observes a dip in light from one of its 156,000 target stars, astronomers catalog the data and use ground-based telescopes to follow up on the planet candidate.

According to Borucki, about half of Kepler's potential discoveries turn out to be false positives. Other systems often include two or three stars, and it is difficult to determine whether a single transit is from a planet or another star.

Kepler has so far found five extrasolar planets, all of which are massive "hot Jupiters" about the size of the gas giant planets in our own solar system.

Scientists hope to announce more planets this winter, Borucki said.

Before the mission launched, Kepler officials advertised finding at least 50 Earth-sized planets inside habitable zones, assuming such worlds are common.

Scientists released Kepler data on more than 150,000 stars in June, including about 300 stars with planetary candidates. Kepler officials retained data on approximately 400 stars to do their own follow-up observations with ground telescopes this summer.

"We found a lot of candidates," Borucki said. "Many of them are smaller than Neptune-sized, and that's wonderful."

The data only covers 43 days of observations because it takes about four months to process observations into usable formats, according to Borucki.

http://www.spaceflightnow.com/news/n1007/28kepler/
 楼主| hkhtg090201 发表于 2010-8-24 13:09 | 显示全部楼层
NASA将于8月27日发布新闻:
NASA to Announce News on “Intriguing Planetary System”
Posted by Doug Messieron August 23, 2010, at 4:15 pmin NASA and NASA Ames.

NASA PRESS RELEASE

NASA will hold a media teleconference Thursday, Aug. 26, at 1 p.m. EDT to discuss the Kepler spacecraft’s latest discovery about an intriguing planetary system.


Kepler, a space observatory, looks for the data signatures of planets by measuring tiny decreases in the brightness of stars when planets cross in front of, or transit, them. In June, mission scientists announced the mission has identified more than 700 planet candidates, including five candidate systems that appear to have more than one transiting planet.

Participating telecon panelists are:

Jon Morse, director, Science Mission Directorate Astrophysics Division, NASA Headquarters, Washington
William Borucki, Kepler Mission science principal investigator, NASA Ames Research Center, Moffett Field, Calif.
Matthew Holman, associate director, Theoretical Astrophysics Division, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.
Alycia Weinberger, astronomer, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington
Audio of the teleconference will be streamed live at: http://www.nasa.gov/newsaudio
cmj9808 发表于 2010-8-24 13:36 | 显示全部楼层
Intriguing Planetary System,很期待
 楼主| hkhtg090201 发表于 2010-8-25 11:36 | 显示全部楼层
最大类太阳系被发现 包含七行星距地球127光年

2010年08月25日 11:10   来源:科学网-kexue.com   卡卡西

    科学家们通过南方天文台发现了一个类似于太阳系的星系,这一星系可能包含7个行星,这是在太阳系以外发现的包含行星最多的星系。据悉,这一星系距离地球大约为127光年。

    这一星系位于水蛇星座,科学家们已经确认这一星系包含有5颗行星,但科学家们通过观测还发现了至少还有2颗行星,不过目前还没有完全确认。一旦捕捉到另外两颗行星,那意味着这是自太阳系之外,人类所发现的包含行星最多的星系。

    欧洲南方天文台的主任克里斯托夫洛维斯博士说:“它可能是我们所发现的行星系统中最大的,而且它和我们所在的太阳系的运行轨迹非常相似,这是一个了不起的成就,我们正在进入一个权限的时代,对于系外行星的研究,我们跨入了一个新的时期。”

    天文学家们耐心的研究了6年的时间,从32颗行星光谱仪中锁定了这5颗具有强烈信号的行星。据悉,这5颗行星的大小是地球的23-25倍之间。与此同时,洛维斯博士还相信存在另外两颗行星。一颗可能类似于土星,围绕它的恒星旋转一周的时间为2200天,另外一颗可能非常靠近恒星。

    对于未知的第二颗行星,洛维斯博士做了解读:“它可能是地球的1.4倍重,在这颗行星上待一年的时间大约为在地球上的1.8天。但是距它所在星系恒星的距离仅为地球和太阳之间距离的2%,这导致它可能过于炎热不可能存在生命。”

    目前科学家们已经发现了15个太阳系外星系,其中都至少包含三颗行星,科学网(kexue.com)查阅资料发现,之前发现的最大的星系是巨蟹星座55星系,它包含5颗行星和2颗气态星体。

    科学家们此前表示,在未来的15年内将可能发现外星生命体,而随着诸多类太阳系的发现,人类也有足够的理由相信,在宇宙中人类绝对不是孤独的。
 楼主| hkhtg090201 发表于 2010-8-27 07:14 | 显示全部楼层
  Kepler找到第一个双行星运输?系统
...在天琴座,2200光年,2个土星大小的行星...

Kepler finds first double planet transiting system
KEITH COOPER...ASTRONOMY NOW
Posted: 26 August 2010


The Kepler space mission has discovered two new Saturn-sized planets and a possible third planet one and a half times bigger than Earth orbiting a star over 2,200 light years away in the constellation Lyra. The discovery also heralds the first time that it has been possible to measure the masses of planets using transit observations.

An artist誷 impression of the two confirmed planets in the Kepler 9 system. Image: NASA/Ames/JPL蠧altech.
Launched in 2009, NASA’s Kepler spacecraft is designed to hunt for extra-solar planets around stars other than our Sun by watching for planets orbiting in front of their stars, and hence blocking some of the starlight. This is called a transit. One of the mission’s first discoveries to be announced is a system of two worlds orbiting the star designated ‘Kepler 9’. One of the planets orbits its star every 19.2 days at a distance of 20.9 million kilometres, and the other every 38.9 days at a distance of 33.8 million kilometres. If placed in our Solar System, both would fall within the orbit of our innermost planet, Mercury, which orbits the Sun every 88 days at a distance of 57.9 million kilometres.

Based on the magnitude of the transits, scientists have been able to judge the size of these worlds as being just slightly smaller than Saturn, but in this case they have been able to measure their masses. Ordinarily the only way to measure the mass of an extra-solar planet is to measure its radial velocity – this is the wobble its gravity imparts on its host star. However, planets can also have a gravitational influence over each other, and this becomes apparent in timing variations in the transits that Kepler is sensitive enough to detect. In other words, the two confirmed planets of the Kepler 9 system, Kepler 9b and 9c, are in a 2:1 orbital resonance, so that for every two orbits that the inner planet 9b makes, the outer plant 9c makes one. When the planets swing past each other, this gravitational resonance tugs on the planets, slightly speeding up or slowing down their transits. Based on the degree of these variations, it is possible to calculate their masses, and from their mass and radius it is possible to work out their density and hence their composition. Kepler 9b and 9c have masses of 0.25 Jupiter masses and 0.17 Jupiter masses respectively, and densities that match gas giant planets made primarily from hydrogen and helium.

TThe dips in light caused by the transits of Kepler 9B and 9c, and possibly a smaller third planet. Image: NASA/Ames/JPL蠧altech.
The planets wound up in this 2:1 orbital resonance after they migrated from their birthplaces further out from the star, before settling into these stable orbits. Alycia Weinberger of the Carnegie Institution in Washington DC, suggests that this could provide insight into the history of this planetary system. “We can work back and figure out what the initial conditions were that led to how they are today, how long their migration lasted, and where they originally formed,” she says.

There are also signs that there is a third planet in the system. Kepler discovered what appears to be a small, rocky planet 1.5 times the diameter of Earth, orbiting even closer to the star with a period of 1.6 days at a distance of four million kilometres. At this stage the third planet has yet to be confirmed, but if it proves to be real then it shows that smaller planets can survive the migration of larger planets around them, says Weinberger. If confirmed, the third planet would be the smallest yet seen by the transit method.

Ultimately, the discovery is a milestone in exoplanet research. “This is the first discovery of multiple planets transiting the same star,” says Kepler’s Principal Investigator, William Borucki of the NASA Ames Research Center. It should be noted that it is not the first discovery of a multiple planet system, only the first by the transit method – radial velocity measurements have found several examples, including the recent five planets discovered around a star by the HARPS radial velocity spectrograph at the European Southern Observatory (see here for more). However, it is impossible to measure the diameter of a planet using the radial velocity method. Now that Kepler has proven it is possible to measure planetary diameters and masses with transits, it will allow many more worlds to be fully characterised.

Intriguingly, the transit timing variations may also enable Kepler to discover additional planets that cannot be seen transiting (because the angle of their orbit is too great to cross the face of their star’s disc), but which still impart a gravitational effect on the planets that do transit. This is similar to how the existence of Neptune was predicted from its gravitational interaction with Uranus. Indeed, alien observers on a distant star watching the transits of the planets in our own Solar System would also see timing variations.

The existence of Kepler 9b and 9c was confirmed by the Keck I telescope on Mauna Kea in Hawaii, which helped to rule out false positives such as variations in the luminosity of the star. In total, ten ground-based telescopes are working overtime to try and confirm the 700 candidate planets discovered by Kepler during the first 43 days of its mission. Regarding the potential third planet in the Kepler 9 system, says Borucki: “Our hope is that in the coming days or weeks we will be able to be more definitive.”

http://astronomynow.com/news/n1008/26kepler/
 楼主| hkhtg090201 发表于 2010-8-27 12:47 | 显示全部楼层
开普勒探测器发现2颗行星"凌日"同一恒星

2010年08月27日 07:51  腾讯科技



    据英国每日邮报报道,8月26日,美国宇航局科学家宣称,最新发现两颗土星大小的巨型行星环绕同一颗恒星运行。这是科学家首次发现2颗行星同时“凌日”于同一颗恒星。

    这两颗系外行星是由开普勒探测器探测到的,这项发现将为科学家理解行星如何形成和它们如何发生交互作用提供至关重要的信息。同时,开普勒科学家发现该行星系统还可能存在第三颗更小的行星,质量大约是地球的1.5倍,其运行轨道距离恒星非常近,公转一周仅1.6天。

    这两颗类似土星的行星分别被命名为“开普勒-9b”和“开普勒-9c”,它们共同环绕距离地球2000光年之遥的一颗恒星。这两颗行星彼此存在引力交互作用,它们的轨道接近于2比1的比率,该现象也被称为“行星共鸣”。同时,这也是第一次发现行星之间存在着轨道引力牵引现象。

    开普勒探测器在为期7个月的勘测活动中,共发现156000颗恒星,该探测器的主要任务是发现太阳系外类似地球质量的行星。

    在这项发现中,开普勒-9b的质量略大一些,其环绕恒星运行一周的时间是19.2天,而开普勒-9c环绕恒星运行一周的时间是38.9天。科学家声称,在更深入的勘测分析中将揭晓第三颗神秘类地行星的面纱。

    开普勒探测器用于寻找适宜居住的行星,这些行星的温度不能过热,也不能过低,应当存在液态水,便于生命存活。
 楼主| hkhtg090201 发表于 2010-9-30 07:31 | 显示全部楼层
可居住的系外行星被发现(其实2007年就宣传过Gliese-581系统)

NASA and NSF-Funded Research Finds First Potentially Habitable Exoplanet

Submitted by keithcowing on Wed, 09/29/2010 - 15:41. Astrobiology


A team of planet hunters from the University of California (UC) Santa Cruz, and the Carnegie Institution of Washington has announced the discovery of a planet with three times the mass of Earth orbiting a nearby star at a distance that places it squarely in the middle of the star's "habitable zone."

This discovery was the result of more than a decade of observations using the W. M. Keck Observatory in Hawaii, one of the world's largest optical telescopes. The research, sponsored by NASA and the National Science Foundation, placed the planet in an area where liquid water could exist on the planet's surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.

To astronomers, a "potentially habitable" planet is one that could sustain life, not necessarily one where humans would thrive. Habitability depends on many factors, but having liquid water and an atmosphere are among the most important.

The new findings are based on 11 years of observations of the nearby red dwarf star Gliese 581using the HIRES spectrometer on the Keck I Telescope. The spectrometer allows precise measurements of a star's radial velocity (its motion along the line of sight from Earth), which can reveal the presence of planets. The gravitational tug of an orbiting planet causes periodic changes in the radial velocity of the host star. Multiple planets induce complex wobbles in the star's motion, and astronomers use sophisticated analyses to detect planets and determine their orbits and masses.

"Keck's long-term observations of the wobble of nearby stars enabled the detection of this multi-planetary system," said Mario R. Perez, Keck program scientist at NASA Headquarters in Washington. "Keck is once again proving itself an amazing tool for scientific research." Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz, and Paul Butler of the Carnegie Institution lead the Lick-Carnegie Exoplanet Survey. The team's new findings are reported in a paper published in the Astrophysical Journal and posted online at: http://arxiv.org

"Our findings offer a very compelling case for a potentially habitable planet," said Vogt. "The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common."

The paper reports the discovery of two new planets around Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system outside of our own. Like our solar system, the planets around Gliese 581 have nearly-circular orbits.




The new planet designated Gliese 581g has a mass three to four times that of Earth and orbits its star in just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and enough gravity to hold on to an atmosphere. Gliese 581, located 20 light years away from Earth in the constellation Libra, has two previously detected planets that lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly-discovered planet g, however, lies right in the middle of the habitable zone.

The planet is tidally locked to the star, meaning that one side is always facing the star and basking in perpetual daylight, while the side facing away from the star is in perpetual darkness. One effect of this is to stabilize the planet's surface climates, according to Vogt. The most habitable zone on the planet's surface would be the line between shadow and light (known as the "terminator").

For more information, visit:
 楼主| hkhtg090201 发表于 2010-10-13 12:21 | 显示全部楼层
最近发现的可居住行星可能不存在
2010年10月13日

两周前,美国天文学家宣布在恒星系Gliese 581发现了一颗可居住的行星,它的大小和表面温度都适合生命生存,它是该星系发现的第五颗行星,编号为Gliese 581g。
然而在本周举行的行星系统天体物理学会议上,瑞士日内瓦天文台的天文学家Francesco Pepe报告,他和他的同事没有在Gliese 581的可居住区域内发现第五颗行星的任何可信信号,他表示无法证实Gliese 581g的存在。
----------
PS:真正的国际玩笑?
您需要登录后才可以回帖 登录 | 注册会员

本版积分规则

QQ|申请友链|旗下论坛|小黑屋|手机版|航空航天港 ( 豫ICP备12024513号 )

GMT+8, 2017-8-17 07:39 , Processed in 0.282869 second(s), 20 queries , Gzip On.

Powered by Discuz! X3.2

© 2001-2013 Comsenz Inc.

快速回复 返回顶部 返回列表