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http://en.wikipedia.org/wiki/HD_85512_b
HD 85512 b
From Wikipedia, the free encyclopedia
HD 85512 b Extrasolar planet List of extrasolar planets
HD85512bWithHZ.svg
Plot of the orbit of HD 85512 b compared to the star's habitable zone.
Parent star
Star HD 85512
Constellation Vela
Right ascension (α) 09h 51m 07.1s
Declination (δ) −43° 30′ 10″
Apparent magnitude (mV) 7.66
Distance 36 [1] ly
(11.1 ± 0.1[2] pc)
Spectral type K5 V
Mass (m) 0.69 M☉
Temperature (T) 4715 ± 102 K
Metallicity [Fe/H] −0.33 ± 0.03
Age 5.61 ± 0.61 Gyr
Orbital elements
Semimajor axis (a) 0.26 ± 0.005[2] AU
Eccentricity (e) 0.11 ± 0.1[2]
Orbital period (P) 54.43 ± 0.13[2] d
Orbital speed (υ) 94.913 ± 0.038 km/s
Physical characteristics
Minimum mass (m sin i) 3.6 ± 0.5 M⊕
Temperature (T) 298[3] K
Discovery information
Discovery date August 17, 2011
Discoverer(s) Pepe et al.
Detection method Radial velocity (HARPS)
Discovery site La Silla Observatory
Discovery status Published
Other designations
CD-42 5678 b, GJ 370 b, Gliese 370 b, HIP 48331 b, LHS 2201 b, NStars 0951-4330 b, YPC 2340 b
Database references
Extrasolar Planets
Encyclopaedia data
SIMBAD data
Artist's impression of HD 85512 b
HD 85512 b is an extrasolar planet[1][2] orbiting the K-type star Gliese 370 approximately 36 light-years away in the constellation of Vela.
Due to its mass of at least 3.6 times the mass of Earth, HD 85512 b is classified as a super-Earth and is one of the smallest exo-planets discovered to be in the habitable zone.[2] HD 85512 b, along with Gliese 581 d is considered to be the best candidate for habitability as of August 25, 2011.[2][4]
Contents
1 Detection and discovery
2 Physical characteristics
3 Habitability
4 See also
5 References
6 External links
[edit] Detection and discovery
The planet was discovered by the scientists at University of Geneva, Switzerland,[4][5] led by the Swiss astronomer Stéphane Udry[6] of the GTO program of High Accuracy Radial velocity Planet Searcher (HARPS), a high-precision echelle spectrograph installed on ESO's 3.6 m telescope at La Silla Observatory in Chile.[3]
[edit] Physical characteristics
On August 17, 2011, researchers released a study of the planet, concluding that HD 85512 b is the most habitable exoplanet discovered up to that point[2] and one of the most stable exo-planets discovered by the High Accuracy Radial Velocity Planet Searcher.[3] The planet has a minimum Earth mass of 3.6 ± 0.5, surface gravity of about 1.4 g and an estimated temperature of 298 K (25 °C or 77 °F) at the top of its atmosphere. The estimated temperature is noted to be similar to temperatures in Southern France,[3][7] but various atmospheric conditions prevalent in the planet have to be analyzed to estimate the temperature of the surface.[3] It orbits the parent star at a distance of about 0.26 AU,[4] with an orbital period of about 54 days.[4]
[edit] Habitability
For the temperature to be below 270 K, for a circular orbit, the planetary albedo should be 0.48 ± 0.05 and for an eccentricity of 0.11, the planetary albedo should be 0.52.[2] If the planet has 50% cloud cover, water may exist in liquid form on the planet[6] provided its atmosphere is similar to our own, thus making the planet habitable.[5][8][9] Also, if the albedo of the planet is increased due to cloud cover, water could be present in its liquid form on the planet, which would mean that the planet is on the edge of habitability.[2][9]
[edit] See also
Portal icon Astronomy portal
Goldilocks planet
Gliese 581 g
Gliese 581 d
Diamond planet
[edit] References
http://news.xinhuanet.com/tech/2011-11/01/c_122218530.htm
地球有个“孪生兄弟” 存在液态水可能性大(图)
2011年11月01日 10:21:32 来源： 羊城晚报 【字号 大小】【留言】【打印】【关闭】
前不久，欧洲的天文学家利用安装在智利的“欧洲南方天文台”，发现了一颗迄今为止跟地球最为“相似”的行星。
据报道，这颗行星位于南天的船帆座，围绕一颗黄矮星运行。距地球大约36光年，质量约为地球质量的3.6倍。根据观测这颗行星围绕恒星运行的距离，科学家认为其地表存在液态水的可能性很大，而液态水对于生命的生存十分关键，因此这颗星球上很有可能存在生命。
这颗让地球人“又惊又喜”的新星被媒体形象地戏称为地球的“孪生兄弟”、“地球第二”，甚至“地球人的舅舅”（既然地球是“母亲”，那么她的“弟弟”也就是“舅舅”了）。但思维严谨的科学家们却只是枯燥地用一串字符和数字称之为“HD85512b”。
这颗行星的轨道几乎是正圆的，这将给它的表面带来持久稳定的气候。如果以我们的太阳系作为参照，它跟恒星黄矮星之间的距离比金星与太阳之间的距离稍稍远些，所处的位置恰好位于生命宜居带的外缘（所谓“宜居带”，是指行星距离其恒星远近适中，其温度范围能允许水以液体状态存在）。在这个距离上，这颗行星从它的“太阳”，即那颗名为HD85512的恒星（黄矮星），得到的热量仅仅比地球从太阳上接收到的热量稍多一些。并且恒星HD85512的年龄要比太阳大一些，也就意味着更加不活跃，这就减小了发生大规模电磁风暴，摧毁整个行星表面大气层这种灾难发生的可能性。
据新星发现者凯尔特那戈博士领导的研究小组所作的计算，它的云覆盖率至少达到50%，这意味着足以能够将多余的热量反射到太空以防止表面过热。相比之下地球的云覆盖率约为60%，“两兄弟”在这方面也大同小异。科学家们还估计，它极有可能拥有与地球类似的大气层，但目前地球人的科学水平“鞭长莫及”，对其大气层的成分，还无法予以确认。 凯尔特那戈博士开玩笑说，既然它远比地球潮湿闷热，引力比地球高出40%，那肯定是练习高温瑜伽的“天然理想之地”。
美国德州大学天文学教授曼富累德·考特兹则谨慎地表示，科学家需要获取更多信息，才能了解这颗新发现的行星究竟是否有生命存在。
令人遗憾的是，限于目前了解宇宙飞船的旅行速度，在可以预见的将来，地球人造访自己的“舅舅”还仅仅只是个梦想。 （编译自美国《纽约时报》等） 唐若水
HD 85512 b
From Wikipedia, the free encyclopedia
HD 85512 b Extrasolar planet List of extrasolar planets
HD85512bWithHZ.svg
Plot of the orbit of HD 85512 b compared to the star's habitable zone.
Parent star
Star HD 85512
Constellation Vela
Right ascension (α) 09h 51m 07.1s
Declination (δ) −43° 30′ 10″
Apparent magnitude (mV) 7.66
Distance 36 [1] ly
(11.1 ± 0.1[2] pc)
Spectral type K5 V
Mass (m) 0.69 M☉
Temperature (T) 4715 ± 102 K
Metallicity [Fe/H] −0.33 ± 0.03
Age 5.61 ± 0.61 Gyr
Orbital elements
Semimajor axis (a) 0.26 ± 0.005[2] AU
Eccentricity (e) 0.11 ± 0.1[2]
Orbital period (P) 54.43 ± 0.13[2] d
Orbital speed (υ) 94.913 ± 0.038 km/s
Physical characteristics
Minimum mass (m sin i) 3.6 ± 0.5 M⊕
Temperature (T) 298[3] K
Discovery information
Discovery date August 17, 2011
Discoverer(s) Pepe et al.
Detection method Radial velocity (HARPS)
Discovery site La Silla Observatory
Discovery status Published
Other designations
CD-42 5678 b, GJ 370 b, Gliese 370 b, HIP 48331 b, LHS 2201 b, NStars 0951-4330 b, YPC 2340 b
Database references
Extrasolar Planets
Encyclopaedia data
SIMBAD data
Artist's impression of HD 85512 b
HD 85512 b is an extrasolar planet[1][2] orbiting the K-type star Gliese 370 approximately 36 light-years away in the constellation of Vela.
Due to its mass of at least 3.6 times the mass of Earth, HD 85512 b is classified as a super-Earth and is one of the smallest exo-planets discovered to be in the habitable zone.[2] HD 85512 b, along with Gliese 581 d is considered to be the best candidate for habitability as of August 25, 2011.[2][4]
Contents
1 Detection and discovery
2 Physical characteristics
3 Habitability
4 See also
5 References
6 External links
[edit] Detection and discovery
The planet was discovered by the scientists at University of Geneva, Switzerland,[4][5] led by the Swiss astronomer Stéphane Udry[6] of the GTO program of High Accuracy Radial velocity Planet Searcher (HARPS), a high-precision echelle spectrograph installed on ESO's 3.6 m telescope at La Silla Observatory in Chile.[3]
[edit] Physical characteristics
On August 17, 2011, researchers released a study of the planet, concluding that HD 85512 b is the most habitable exoplanet discovered up to that point[2] and one of the most stable exo-planets discovered by the High Accuracy Radial Velocity Planet Searcher.[3] The planet has a minimum Earth mass of 3.6 ± 0.5, surface gravity of about 1.4 g and an estimated temperature of 298 K (25 °C or 77 °F) at the top of its atmosphere. The estimated temperature is noted to be similar to temperatures in Southern France,[3][7] but various atmospheric conditions prevalent in the planet have to be analyzed to estimate the temperature of the surface.[3] It orbits the parent star at a distance of about 0.26 AU,[4] with an orbital period of about 54 days.[4]
[edit] Habitability
For the temperature to be below 270 K, for a circular orbit, the planetary albedo should be 0.48 ± 0.05 and for an eccentricity of 0.11, the planetary albedo should be 0.52.[2] If the planet has 50% cloud cover, water may exist in liquid form on the planet[6] provided its atmosphere is similar to our own, thus making the planet habitable.[5][8][9] Also, if the albedo of the planet is increased due to cloud cover, water could be present in its liquid form on the planet, which would mean that the planet is on the edge of habitability.[2][9]
[edit] See also
Portal icon Astronomy portal
Goldilocks planet
Gliese 581 g
Gliese 581 d
Diamond planet
[edit] References
http://news.xinhuanet.com/tech/2011-11/01/c_122218530.htm
地球有个“孪生兄弟” 存在液态水可能性大(图)
2011年11月01日 10:21:32 来源： 羊城晚报 【字号 大小】【留言】【打印】【关闭】
前不久，欧洲的天文学家利用安装在智利的“欧洲南方天文台”，发现了一颗迄今为止跟地球最为“相似”的行星。
据报道，这颗行星位于南天的船帆座，围绕一颗黄矮星运行。距地球大约36光年，质量约为地球质量的3.6倍。根据观测这颗行星围绕恒星运行的距离，科学家认为其地表存在液态水的可能性很大，而液态水对于生命的生存十分关键，因此这颗星球上很有可能存在生命。
这颗让地球人“又惊又喜”的新星被媒体形象地戏称为地球的“孪生兄弟”、“地球第二”，甚至“地球人的舅舅”（既然地球是“母亲”，那么她的“弟弟”也就是“舅舅”了）。但思维严谨的科学家们却只是枯燥地用一串字符和数字称之为“HD85512b”。
这颗行星的轨道几乎是正圆的，这将给它的表面带来持久稳定的气候。如果以我们的太阳系作为参照，它跟恒星黄矮星之间的距离比金星与太阳之间的距离稍稍远些，所处的位置恰好位于生命宜居带的外缘（所谓“宜居带”，是指行星距离其恒星远近适中，其温度范围能允许水以液体状态存在）。在这个距离上，这颗行星从它的“太阳”，即那颗名为HD85512的恒星（黄矮星），得到的热量仅仅比地球从太阳上接收到的热量稍多一些。并且恒星HD85512的年龄要比太阳大一些，也就意味着更加不活跃，这就减小了发生大规模电磁风暴，摧毁整个行星表面大气层这种灾难发生的可能性。
据新星发现者凯尔特那戈博士领导的研究小组所作的计算，它的云覆盖率至少达到50%，这意味着足以能够将多余的热量反射到太空以防止表面过热。相比之下地球的云覆盖率约为60%，“两兄弟”在这方面也大同小异。科学家们还估计，它极有可能拥有与地球类似的大气层，但目前地球人的科学水平“鞭长莫及”，对其大气层的成分，还无法予以确认。 凯尔特那戈博士开玩笑说，既然它远比地球潮湿闷热，引力比地球高出40%，那肯定是练习高温瑜伽的“天然理想之地”。
美国德州大学天文学教授曼富累德·考特兹则谨慎地表示，科学家需要获取更多信息，才能了解这颗新发现的行星究竟是否有生命存在。
令人遗憾的是，限于目前了解宇宙飞船的旅行速度，在可以预见的将来，地球人造访自己的“舅舅”还仅仅只是个梦想。 （编译自美国《纽约时报》等） 唐若水
