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Revised Masses and Densities of the Planets around Kepler-10

Weiss, Lauren M. and Rogers, Leslie A. and Isaacson, Howard T. and Agol, Eric and Marcy, Geoffrey W. and Rowe, Jason F. and Kipping, David and Fulton, Benjamin J. and Lissauer, Jack J. and Howard, Andrew W. and Fabrycky, Daniel (2016) Revised Masses and Densities of the Planets around Kepler-10. Astrophysical Journal, 819 (1). Art. No. 83. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20160419-084945218

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Abstract

Determining which small exoplanets have stony-iron compositions is necessary for quantifying the occurrence of such planets and for understanding the physics of planet formation. Kepler-10 hosts the stony-iron world Kepler-10b, and also contains what has been reported to be the largest solid silicate-ice planet, Kepler-10c. Using 220 radial velocities (RVs), including 72 precise RVs from Keck-HIRES of which 20 are new from 2014 to 2015, and 17 quarters of Kepler photometry, we obtain the most complete picture of the Kepler-10 system to date. We find that Kepler-10b (R_p = 1.47 R_⊕) has mass 3.72 ± 0.42 M_⊕ and density 6.46 ± 0.73 g cm^(-3). Modeling the interior of Kepler-10b as an iron core overlaid with a silicate mantle, we find that the iron core constitutes 0.17 ± 0.11 of the planet mass. For Kepler-10c (R_p = 2.35 R_⊕) we measure mass 13.98 ± 1.79 M_⊕ and density 5.94 ± 0.76 g cm^(-3), significantly lower than the mass computed in Dumusque et al. (17.2 ± 1.9 M_⊕). Our mass measurement of Kepler-10c rules out a pure stony-iron composition. Internal compositional modeling reveals that at least 10% of the radius of Kepler-10c is a volatile envelope composed of hydrogen–helium (0.2% of the mass, 16% of the radius) or super-ionic water (28% of the mass, 29% of the radius). However, we note that analysis of only HIRES data yields a higher mass for planet b and a lower mass for planet c than does analysis of the HARPS-N data alone, with the mass estimates for Kepler-10 c being formally inconsistent at the 3σ level. Moreover, dividing the data for each instrument into two parts also leads to somewhat inconsistent measurements for the mass of planet c derived from each observatory. Together, this suggests that time-correlated noise is present and that the uncertainties in the masses of the planets (especially planet c) likely exceed our formal estimates. Transit timing variations (TTVs) of Kepler-10c indicate the likely presence of a third planet in the system, KOI-72.X. The TTVs and RVs are consistent with KOI-72.X having an orbital period of 24, 71, or 101 days, and a mass from 1 to 7 M_⊕.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.3847/0004-637X/819/1/83DOIArticle
http://iopscience.iop.org/article/10.3847/0004-637X/819/1/83PublisherArticle
http://arxiv.org/abs/1601.06168arXivDiscussion Paper
ORCID:
AuthorORCID
Weiss, Lauren M.0000-0002-3725-3058
Rogers, Leslie A.0000-0003-0638-3455
Isaacson, Howard T.0000-0002-0531-1073
Agol, Eric0000-0002-0802-9145
Marcy, Geoffrey W.0000-0002-2909-0113
Rowe, Jason F.0000-0002-5904-1865
Fulton, Benjamin J.0000-0003-3504-5316
Lissauer, Jack J.0000-0001-6513-1659
Howard, Andrew W.0000-0001-8638-0320
Fabrycky, Daniel0000-0003-3750-0183
Additional Information:© 2016. The American Astronomical Society. Received 2015 August 12; accepted 2016 January 20; published 2016 March 1. LMW gratefully acknowledges support from Kenneth and Gloria Levy. This research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915 via the Dynamics of Exoplanets workshop at the Kavli Institute for Theoretical Physics in Santa Barbara, CA. We thank Tsevi Mazeh for informative discussions regarding time-correlated noise. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Maunakea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible.
Funders:
Funding AgencyGrant Number
Kenneth and Gloria LevyUNSPECIFIED
NSFPHY11-25915
Subject Keywords:planetary systems; planets and satellites: composition; planets and satellites: detection; planets and satellites: fundamental parameters; planets and satellites: terrestrial planets; techniques: radial velocities
Issue or Number:1
Record Number:CaltechAUTHORS:20160419-084945218
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160419-084945218
Official Citation:Lauren M. Weiss et al 2016 ApJ 819 83
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66272
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:19 Apr 2016 18:02
Last Modified:09 Mar 2020 13:19

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