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New Formation Models for the Kepler-36 System

Bodenheimer, Peter and Stevenson, David J. and Lissauer, Jack J. and D’Angelo, Gennaro (2018) New Formation Models for the Kepler-36 System. Astrophysical Journal, 868 (2). Art. No. 138. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20181203-154118113

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Abstract

Formation of the planets in the Kepler-36 system is modeled by detailed numerical simulations according to the core-nucleated accretion scenario. The standard model is updated to include the dissolution of accreting rocky planetesimals in the gaseous envelope of the planet, leading to substantial enrichment of the envelope mass in heavy elements and a non-uniform composition with depth. For Kepler-36 c, models involving in situ formation and models involving orbital migration are considered. The results are compared with standard formation models. The calculations include the formation (accretion) phase as well as the subsequent cooling phase, up to the age of Kepler-36 (7 Gyr). During the latter phase, mass loss induced by stellar XUV radiation is included. In all cases, the results fit the measured mass, 7.84 M⊕, and radius, 3.68 R⊕, of Kepler-36 c. Two parameters are varied to obtain these fits: the disk solid surface density at the formation location and the "efficiency" factor in the XUV mass-loss rate. The updated models are hotter and therefore less dense in the silicate portion of the planet and in the overlying layers of H/He, as compared with standard models. The lower densities mean that only about half as much H/He is needed to be accreted to fit the present-day mass and radius constraints. For Kepler-36 b, an updated in situ calculation shows that the entire H/He envelope is lost, early in the cooling phase, in agreement with observation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/aae928DOIArticle
https://arxiv.org/abs/1810.07160arXivDiscussion Paper
ORCID:
AuthorORCID
Bodenheimer, Peter0000-0001-6093-3097
Stevenson, David J.0000-0001-9432-7159
D’Angelo, Gennaro0000-0002-2064-0801
Additional Information:© 2018 The American Astronomical Society. Received 2018 June 28; revised 2018 October 5; accepted 2018 October 15; published 2018 December 3. Primary funding for the code development for this project was provided by the NASA Emerging Worlds program 15-EW15_2-0007; the specific calculations for the Kepler-36 planets were funded by the NASA Origins of Solar Systems Program grant NNX14AG92G. We are indebted to Ravit Helled, who provided the equation of state tables for compositions that include silicates. We thank Stuart Weidenschilling for informative discussions and Anthony Dobrovolskis for useful comments on the manuscript. We thank the referee for a careful review, which led to improvements in the manuscript. Resources supporting the work presented herein were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center.
Funders:
Funding AgencyGrant Number
NASA15-EW15_2-0007
NASANNX14AG92G
Subject Keywords:planets and satellites: formation – planets and satellites: individual (Kepler-36 c,Kepler-36 b) – planets and satellites: physical evolution
Issue or Number:2
Record Number:CaltechAUTHORS:20181203-154118113
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20181203-154118113
Official Citation:Peter Bodenheimer et al 2018 ApJ 868 138
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91410
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Dec 2018 04:40
Last Modified:03 Oct 2019 20:34

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