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A chthonian planet (, sometimes 'cthonian') is a hypothetical class of celestial objects resulting from the stripping away of a gas giant's hydrogen and helium atmosphere and outer layers, which is called hydrodynamic escape. Such atmospheric stripping is a likely result of proximity to a star. The remaining rocky or metallic core would resemble a terrestrial planet in many respects.〔Hébrard G., Lecavelier Des Étangs A., Vidal-Madjar A., Désert J.-M., Ferlet R. (2003), (''Evaporation Rate of Hot Jupiters and Formation of chthonian Planets'' ), Extrasolar Planets: Today and Tomorrow, ASP Conference Proceedings, Vol. 321, held 30 June – 4 July 2003, Institut d'astrophysique de Paris, France. Edited by Jean-Philippe Beaulieu, Alain Lecavelier des Étangs and Caroline Terquem.〕 HD 209458 b is an example of a planet that is in the process of having its atmosphere stripped away, though it is not itself a chthonian planet nor is it expected to become one in the near future. A similar case would be Gliese 436b, as it has lost already a 10% of its atmosphere. COROT-7b may be the first chthonian planet discovered.〔 〕 ''Chthonia'' (from (ギリシア語:Χθών)) means "of the Earth". The term was coined by Hébrard et al., since the term ''chthonian'' generally refers to Greek deities from the infernal underground. == See also == * COROT-7b: diameter 1.7 × Earth, mass 4.8 × Earth, orbital period = 20.5 hours〔(【引用サイトリンク】url=http://exoplanet.eu/planet.php?p1=CoRoT-7&p2=b )〕 (super-Earth candidate) * Hot Jupiter * Hypothetical astronomical object * Kepler-70 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「chthonian planet」の詳細全文を読む スポンサード リンク
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