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Could we identify hot ocean-planets with CoRoT, Kepler and Doppler velocimetry?

Selsis, F. and Chazelas, B. and Bordé, P. and Ollivier, M. and Brachet, F. and Decaudin, M. and Bouchy, F. and Ehrenreich, D. and Grießmeier, J.-M. and Lammer, H. and Sotin, C. and Grasset, O. and Moutou, C. and Barge, P. and Deleuil, M. and Mawet, D. and Despois, D. and Kasting, J. F. and Léger, A. (2007) Could we identify hot ocean-planets with CoRoT, Kepler and Doppler velocimetry? Icarus, 191 (2). pp. 453-468. ISSN 0019-1035.

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Planets less massive than about 10 MEarth are expected to have no massive H–He atmosphere and a cometary composition (∼50% rocks, 50% water, by mass) provided they formed beyond the snowline of protoplanetary disks. Due to inward migration, such planets could be found at any distance between their formation site and the star. If migration stops within the habitable zone, this may produce a new kind of planets, called ocean-planets. Ocean-planets typically consist in a silicate core, surrounded by a thick ice mantle, itself covered by a 100 km-deep ocean. The possible existence of ocean-planets raises important astrobiological questions: Can life originate on such body, in the absence of continent and ocean–silicate interfaces? What would be the nature of the atmosphere and the geochemical cycles? In this work, we address the fate of hot ocean-planets produced when migration ends at a closer distance. In this case the liquid/gas interface can disappear, and the hot H_2O envelope is made of a supercritical fluid. Although we do not expect these bodies to harbor life, their detection and identification as water-rich planets would give us insight as to the abundance of hot and, by extrapolation, cool ocean-planets. The water reservoir of these planets seems to be weakly affected by gravitational escape, provided that they are located beyond some minimum distance, e.g. 0.04 AU for a 5-Earth-mass planet around a Sun-like star. The swelling of their water atmospheres by the high stellar flux is expected not to significantly increase the planets' radii. We have studied the possibility of detecting and characterizing these hot ocean-planets by measuring their mean densities using transit missions in space—CoRoT (CNES) and Kepler (NASA)—in combination with Doppler velocimetry from the ground—HARPS (ESO) and possible future instruments. We have determined the domain in the [stellar magnitude, orbital distance] plane where discrimination between ocean-planets and rocky planets is possible with these instruments. The brightest stars of the mission target lists and the planets closest to their stars are the most favorable cases. Full advantage of high precision photometry by CoRoT, and particularly Kepler, can be obtained only if a new generation of Doppler instruments is built.

Item Type:Article
Related URLs:
URLURL TypeDescription
Selsis, F.0000-0001-9619-5356
Ehrenreich, D.0000-0001-9704-5405
Mawet, D.0000-0002-8895-4735
Kasting, J. F.0000-0003-4042-2067
Additional Information:© 2007 Elsevier Inc. Received 21 July 2006; revised 8 April 2007. Available online 1 May 2007. We are grateful to Odile Dutuit, Roland Thissen, Alexandro Morbidelli, and David Koch for valuable discussions on the water molecule absorption in the EUV, the possible abundance of these putative planets and precise information on Kepler, respectively. We are also grateful to an anonymous referee and to Marc Kuchner for valuable comments on our initial manuscript. This work was supported by CNRS and CNES in part by the Programme National de Planétologie and the Groupe de Recherche “Exobio,” and under contract 1256791 with the Jet Propulsion Laboratory (JPL) funded by NASA through the Michelson Fellowship Program. We also acknowledge the benefit from the ISSI Team “Evolution of Habitable Planets.”
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Programme National de Planétologie (PNP)1256791
NASA Michelson FellowshipUNSPECIFIED
Subject Keywords:Extrasolar planets; Ices; Planets migration
Issue or Number:2
Record Number:CaltechAUTHORS:20150519-143035564
Persistent URL:
Official Citation:F. Selsis, B. Chazelas, P. Bordé, M. Ollivier, F. Brachet, M. Decaudin, F. Bouchy, D. Ehrenreich, J.-M. Grießmeier, H. Lammer, C. Sotin, O. Grasset, C. Moutou, P. Barge, M. Deleuil, D. Mawet, D. Despois, J.F. Kasting, A. Léger, Could we identify hot ocean-planets with CoRoT, Kepler and Doppler velocimetry?, Icarus, Volume 191, Issue 2, 15 November 2007, Pages 453-468, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57670
Deposited By: Ruth Sustaita
Deposited On:19 May 2015 23:57
Last Modified:09 Mar 2020 13:19

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