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An asteroseismic view of the radius valley: stripped cores, not born rocky

Van Eylen, V. and Agentoft, Camilla and Lundkvist, M. S. and Kjeldsen, H. and Owen, J. E. and Fulton, B. J. and Petigura, E. and Snellen, I. (2018) An asteroseismic view of the radius valley: stripped cores, not born rocky. Monthly Notices of the Royal Astronomical Society, 479 (4). pp. 4786-4795. ISSN 0035-8711. doi:10.1093/mnras/sty1783.

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Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley, i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈2R⊕. Such a valley has been observed recently, owing to an improvement in the precision of stellar and therefore planetary radii. Here, we investigate the presence, location, and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3 per cent. We detect a clear bimodal distribution, with super-Earths (≈1.5R⊕) and sub-Neptunes (≈2.5 R⊕) separated by a deficiency around 2R⊕. We furthermore characterize the slope of the valley as a power law R∝Pγ with γ=−0.09^(+0.02)_(−0.04). A negative slope is consistent with models of photoevaporation, but not with the late formation of rocky planets in a gas-poor environment, which would lead to a slope of opposite sign. The exact location of the gap further points to planet cores consisting of a significant fraction of rocky material.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Van Eylen, V.0000-0001-5542-8870
Fulton, B. J.0000-0003-3504-5316
Petigura, E.0000-0003-0967-2893
Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 June 29. Received 2018 June 28; in original form 2016 November 28. Published: 06 July 2018. We thank the anonymous referee for helpful comments and suggestions that have improved this manuscript. We thank Alan Heavens for discussions on support vector machines. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant DNRF106). IS acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 694513. The research was supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (Grant agreement no.: 267864). MSL is supported by The Independent Research Fund Denmark’s Sapere Aude program (Grant agreement no.: DFF–5051-00130). This research was made with the use of NASA’s Astrophysics Data System and the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Danish National Research FoundationDNRF106
European Research Council (ERC)694513
European Research Council (ERC)267864 ASTERISK
Danish Council for Independent ResearchDFF-5051-00130
Subject Keywords:planets and satellites: composition – planets and satellites: formation – planets and satellites: fundamental parameters – planets and satellites: physical evolution
Issue or Number:4
Record Number:CaltechAUTHORS:20180105-102805990
Persistent URL:
Official Citation:V Van Eylen, Camilla Agentoft, M S Lundkvist, H Kjeldsen, J E Owen, B J Fulton, E Petigura, I Snellen; An asteroseismic view of the radius valley: stripped cores, not born rocky, Monthly Notices of the Royal Astronomical Society, Volume 479, Issue 4, 1 October 2018, Pages 4786–4795,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84124
Deposited By: Melissa Ray
Deposited On:05 Jan 2018 19:23
Last Modified:15 Nov 2021 20:17

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