查看“︁克卜勒37b”︁的源代码

{{noteTA
|G1=Astronomy
|G2=單位
|T=zh-cn:开普勒37b; zh-tw:克卜勒37b; zh-hk:開普勒37b
|1=zh-cn:空间望远镜; zh-tw:太空望遠鏡; zh-hk:太空望遠鏡;
}}
{{Infobox planet
| name               = 克卜勒37b<br />{{lang|en|Kepler-37b}}
| image              = [[File:Kepler-37b.jpg|200px|克卜勒37b想像圖]]
| caption            = 藝術家筆下的克卜勒37b想像圖
| apsis              = astron
| discovery_ref      = <ref name=nature></ref>
| discoverer         = 
| discovery_site     = 
| discovered         = 2013年2月20日宣布<ref name=nature></ref>
| discovery_method   = [[系外行星偵測法#凌日法|凌日法]]
| alt_names          = <!--(Any alternative names for the body)-->
| periastron         = 
| apoastron          = 
| semimajor          = 0.1003 [[天文單位|AU]]<ref name=keplernasa></ref>
| avg_speed          = 
| eccentricity       = 
| period             = 13.367308日<ref name=keplernasa>{{cite web |url=http://kepler.nasa.gov/Mission/discoveries/kepler37/ |title=Kepler-37 System |publisher=kepler.nasa.gov |date= |accessdate=February 21, 2013 |archive-url=https://web.archive.org/web/20130516185827/http://kepler.nasa.gov/Mission/discoveries/kepler37/ |archive-date=2013-05-16 |dead-url=yes }}</ref>
| inclination        = 88.63°<ref name=keplernasa></ref>
| angular_dist       = 
| long_periastron    = <!--(Longitude of periastron)-->
| time_periastron    = <!--(Time of periastron)-->
| semi-amplitude     = 
| mean_radius        = 1930公里（0.303 [[地球半徑|<math>R_\oplus</math>]]）<ref name=keplernasa></ref>
| surface_area       = 
| volume             = 
| density            = 
| mass               = ≥0.01 [[地球質量|M⊕]]
| surface_grav       = <!--Equatorial surface gravity-->
| escape_velocity    = 
| albedo             = 
| single_temperature = 700 [[開氏溫標|K]]<ref name=NASA></ref>
}}

'''克卜勒37b'''（{{lang en|'''Kepler-37b'''}}）是一顆位於[[天琴座]]的[[太陽系外行星]]，其母恆星是[[克卜勒37]]。截至2013年2月，這顆行星是[[天文學家]]發現體積最小的系外行星，其質量和半徑僅稍大於[[月球]]，比[[水星]]還要小。<ref name=SWR>{{cite web |url=http://www.scienceworldreport.com/articles/5098/20130221/tiniest-planet-discovered-nasa-outside-solar-system.htm |title=Tiniest Planet Yet Discovered by NASA Outside our Solar System |publisher=scienceworldreport.com |date=February 21, 2013 |accessdate=February 21, 2013 |archive-date=2019-09-09 |archive-url=https://web.archive.org/web/20190909011628/http://www.scienceworldreport.com/articles/5098/20130221/tiniest-planet-discovered-nasa-outside-solar-system.htm |dead-url=no }}</ref><ref name="space.com kepler-37b">{{Cite web |url=http://www.space.com/19858-smallest-alien-planet-kepler-37b-infographic.html |title=Smallest Alien Planet Kepler-37b Explained (Infographic) |accessdate=2014-01-06 |archive-date=2020-01-01 |archive-url=https://web.archive.org/web/20200101164921/https://www.space.com/19858-smallest-alien-planet-kepler-37b-infographic.html |dead-url=no }}</ref>

==發現==
克卜勒37b和位於同一個[[行星系]]的另外兩顆行星{{link-en|克卜勒37c|Kepler-37c}}、{{link-en|克卜勒37d|Kepler-37d}}一起被[[克卜勒太空望遠鏡]]以觀測[[凌 (天體)|凌星現象]]的方式，即[[系外行星偵測法#凌日法|凌日法]]發現<ref name=NASA></ref><ref name=nature>{{cite journal |last1=Barclay |first1=T. |last2=Rowe |first2=J. F. |last3=Lissauer |first3=J. J. |last4=Huber |first4=D. |last5=Fressin |first5=F. |last6=Howell |first6=S. B. |last7=Bryson |first7=S. T. |last8=Chaplin |first8=W. J. |last9=Désert |first9=J. M. |title=A sub-Mercury-sized exoplanet |url=http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11914.html 
|journal=[[Nature (journal)]] |date=2013-02-20 |issn=0028-0836 |doi=10.1038/nature11914 |accessdate=2013-02-21 |arxiv=1305.5587 |bibcode=2013Natur.494..452B }}</ref>。

為了得知該行星的精確體積，天文學家利用聲波量測比較它們和母恆星的體積<ref name=NASA></ref>，這個測量方式正是應用[[星震學]]的典型例子。而且，克卜勒37本身也是至今以星震學觀測的體積最小的恆星<ref name=NASA></ref><ref name=slate></ref>。這些研究允許天文學家量測行星體積時，可以得到極高的精確度<ref name=NASA></ref>。

另外，克卜勒37b自發現至今，一直都是太陽系外環繞[[主序星]]公轉的體積最小的行星<ref name=SWR></ref><ref name="konacki2003">{{cite journal | url=http://www.iop.org/EJ/article/1538-4357/591/2/L147/17269.html | author=Konacki, M., Wolszczan, A. | title=Masses and Orbital Inclinations of Planets in the PSR B1257+12 System | journal=The [[Astrophysical Journal]] | volume=591 | issue=2 | pages=L147–L150 | year=2003 | doi=10.1086/377093 | bibcode=2003ApJ...591L.147K | arxiv=astro-ph/0305536 | access-date=2013-12-16 | archive-date=2020-01-04 | archive-url=https://web.archive.org/web/20200104010006/http://www.iop.org/EJ/article/1538-4357/591/2/L147/17269.html | dead-url=no }}</ref><ref group="note">尚未確認存在的[[脈衝星行星]][[PSR B1257+12 D]]的質量遠小於克卜勒37b；而[[PSR B1257+12 A]]的質量則與克卜勒37b相當。目前這些行星的實際體積尚未確認，但這兩顆脈衝星行星的體積可能小於克卜勒37b。</ref>。天文學家指出，他們能輕易且迅速地發現這顆行星，全因其[[軌道週期]]短促、高相對亮度、以及其母星的活性較低。<ref>{{Cite web |url=http://www.centauri-dreams.org/?p=26604 |title=Centauri Dreams - Small Planets Confirm Kepler’s Capabilities |accessdate=2013-12-16 |archive-date=2013-12-02 |archive-url=https://web.archive.org/web/20131202223326/http://www.centauri-dreams.org/?p=26604 |dead-url=no }}</ref>[[美國航空航天局]][[艾姆斯研究中心]]的天文學家[[傑克·喬納森·利斯奧爾]]指出，克卜勒37b的發現代表著有許多類似的體積小的系外行星存在<ref name=NASA></ref>。

==行星狀態==
===物理特徵===
[[File:A Moon-size Line Up.jpg|thumb|200px|克卜勒37b的體積只稍大於月球，是至今已知體積最小的系外行星。]]

克卜勒37b距離地球210[[光年]]<ref name=latimes>{{cite web |url=http://www.latimes.com/news/science/la-sci-small-exoplanet-20130221,0,4749761.story |title=NASA, using Kepler space telescope, finds smallest planet yet |publisher=[[Los Angeles Times]] |date=February 20, 2013 |accessdate=February 21, 2013 |archive-date=2013-02-22 |archive-url=https://web.archive.org/web/20130222004513/http://www.latimes.com/news/science/la-sci-small-exoplanet-20130221,0,4749761.story |dead-url=no }}</ref>，其質量小於[[地球質量]]的1%，即小於5.9722 × 10<sup>22</sup> 公斤<ref name="earth-sse">{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Earth&Display=Facts |title=Solar System Exploration: Earth: Facts & Figures |work=NASA |date=14 Feb 2011 |accessdate=2011-05-05 |archive-date=2015-04-19 |archive-url=https://web.archive.org/web/20150419035450/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Earth&Display=Facts |dead-url=no }}</ref>，稍低於月球（1.23%地球質量，即7.3459 × 10<sup>22</sup> 公斤）。<ref name="W06">
{{cite journal
| last1 = Wieczorek
| first1 = M.
| title = The constitution and structure of the lunar interior
| journal = Reviews in Mineralogy and Geochemistry
| volume = 60
| issue = 1
| pages = 221–364
| year = 2006
| doi = 10.2138/rmg.2006.60.3
| author2 = <nowiki><Please add first missing authors to populate metadata.></nowiki>
}}
</ref>其半徑為1,932.5[[公里]]，稍大於月球（半徑為1,738.14公里）<ref name="NSSDC">{{cite web
| last = Williams
| first = Dr. David R.
| title = Moon Fact Sheet
| publisher = [[NASA]] (National Space Science Data Center)
| url = http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html
| date = 2 February 2006
| accessdate = 31 December 2008
| archive-date = 2010-03-23
| archive-url = https://web.archive.org/web/20100323165650/http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html
| dead-url = no
}}</ref>，僅為[[地球半径]]（6,378.137公里）的30.3%<ref name=slate>{{cite web |url=http://www.slate.com/blogs/bad_astronomy/2013/02/20/smallest_exoplanet_kepler_37b_is_barely_bigger_than_earth_s_moon.html |title=Astronomers Find the Tiniest Exoplanet Yet |publisher=[[板岩 (雜誌)]] |date=February 20, 2013 |accessdate=February 21, 2013 |archive-date=2013-02-22 |archive-url=https://web.archive.org/web/20130222014636/http://www.slate.com/blogs/bad_astronomy/2013/02/20/smallest_exoplanet_kepler_37b_is_barely_bigger_than_earth_s_moon.html |dead-url=no }}</ref>，並且是至今已知體積最大行星[[HAT-P-32b]]半徑（2.037[[木星半徑]]，145,629.204公里）的1.33%<ref>{{cite web |url=http://www.exoplanet.eu/star.php?st=HAT-P-32#a_publi |title=Notes for star HAT-P-32 |author=Jean Schneider |year=2011 |work= |publisher=[[太陽系外行星百科|Extrasolar Planets Encyclopaedia]] |accessdate=15 June 2011 |archive-date=2012-05-05 |archive-url=https://web.archive.org/web/20120505092649/http://exoplanet.eu/star.php?st=HAT-P-32#a_publi |dead-url=no }}</ref>。[[美國航空航天局]]指出，這顆行星很可能沒有[[大氣層]]，無法讓[[生命]]存在<ref name=NASA>{{cite web |url=http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-057_Kepler_Tiny_Planet.html |title=NASA's Kepler Mission Discovers Tiny Planet System |publisher=[[NASA]] |date=February 20, 2013 |accessdate=February 21, 2013 |archive-date=2018-09-08 |archive-url=https://web.archive.org/web/20180908041134/https://www.nasa.gov/home/hqnews/2013/feb/HQ_13-057_Kepler_Tiny_Planet.html |dead-url=no }}</ref>。此外，這顆行星很可能由岩石物質組成<ref name=NASA></ref>。

===軌道特徵===
克卜勒37b的半長軸為0.1003 [[天文單位|AU]]，即約1,500萬公里（9.3萬英里）<ref name=keplernasa></ref>。因為克卜勒37b是行星系中最靠近母恆星的行星（其半長軸是[[水星]]的1/3<ref name="horizons">{{cite web | date=April 7, 2008 | first=Donald K. | last=Yeomans | url=http://ssd.jpl.nasa.gov/?horizons | title=HORIZONS System | publisher=NASA JPL | accessdate=2008-04-07 | archive-date=2007-03-28 | archive-url=https://web.archive.org/web/20070328180634/http://ssd.jpl.nasa.gov/?horizons | dead-url=no }}</ref>，即1,500,466公里），故其軌道週期僅約為13個[[地球日]]<ref name=SWR></ref>。其與恆星的距離是如此的接近，致使母星將其表面加熱，平均溫度估計高達700 [[熱力學溫標|K]]（425 [[摄氏温标|°C]]）<ref name=NASA></ref>。除此以外，另外兩顆行星克卜勒37c和克卜勒37d的軌道週期亦分別和37b呈8:5和3:1共振<ref name=nature></ref><ref name=keplernasa></ref>。

==注釋==
{{Reflist|group=note}}

==參考資料==
{{reflist|2}}

[[Category:2013年发现的系外行星]]
[[Category:凌星現象]]
[[Category:天琴座]]
[[Category:類地行星]]
[[Category:克卜勒太空望遠鏡發現的系外行星]]