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Title: Formation, tidal evolution, and habitability of the Kepler-186 system

Abstract

The Kepler-186 system consists of five planets orbiting an early M dwarf. The planets have physical radii of 1.0-1.50 R {sub ⊕} and orbital periods of 4-130 days. The 1.1 R {sub ⊕} Kepler-186f with a period of 130 days is of particular interest. Its insolation of roughly 0.32 S {sub ⊕} places it within the surface liquid water habitable zone (HZ). We present a multifaceted study of the Kepler-186 system, using two sets of parameters which are consistent with the data and also self-consistent. First, we show that the distribution of planet masses can be roughly reproduced if the planets were accreted from a high surface density disk presumably sculpted by an earlier phase of migration. However, our simulations predict the existence of one to two undetected planets between planets e and f. Next, we present a dynamical analysis of the system including the effect of tides. The timescale for tidal evolution is short enough that the four inner planets must have small obliquities and near-synchronous rotation rates. The tidal evolution of Kepler-186f is slow enough that its current spin state depends on a combination of its initial spin state, its dissipation rate, and the stellar age. Finally, wemore » study the habitability of Kepler-186f with a one-dimensional climate model. The planet's surface temperature can be raised above 273 K with 0.5-5 bars of CO{sub 2}, depending on the amount of N{sub 2} present. Kepler-186f represents a case study of an Earth-sized planet in the cooler regions of the HZ of a cool star.« less

Authors:
; ; ;  [1];  [2];  [3];  [4]
  1. Univ. Bordeaux, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, F-33270 Floirac (France)
  2. Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Rutherfordstrasse 2, D-12489 Berlin (Germany)
  3. SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States)
  4. NASA Ames Research Center, Moffett Field, CA 94035 (United States)
Publication Date:
OSTI Identifier:
22365065
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON DIOXIDE; DENSITY; DISTRIBUTION; DWARF STARS; EVOLUTION; HEAT EXCHANGERS; INSOLATION; MASS; ONE-DIMENSIONAL CALCULATIONS; PLANETS; ROTATION; SATELLITE ATMOSPHERES; SATELLITES; SIMULATION; SPIN; STABILITY; STARS; SURFACES; WATER

Citation Formats

Bolmont, Emeline, Raymond, Sean N., Selsis, Franck, Hersant, Franck, Von Paris, Philip, Quintana, Elisa V., and Barclay, Thomas, E-mail: bolmont@obs.u-bordeaux1.fr. Formation, tidal evolution, and habitability of the Kepler-186 system. United States: N. p., 2014. Web. doi:10.1088/0004-637X/793/1/3.
Bolmont, Emeline, Raymond, Sean N., Selsis, Franck, Hersant, Franck, Von Paris, Philip, Quintana, Elisa V., & Barclay, Thomas, E-mail: bolmont@obs.u-bordeaux1.fr. Formation, tidal evolution, and habitability of the Kepler-186 system. United States. doi:10.1088/0004-637X/793/1/3.
Bolmont, Emeline, Raymond, Sean N., Selsis, Franck, Hersant, Franck, Von Paris, Philip, Quintana, Elisa V., and Barclay, Thomas, E-mail: bolmont@obs.u-bordeaux1.fr. Sat . "Formation, tidal evolution, and habitability of the Kepler-186 system". United States. doi:10.1088/0004-637X/793/1/3.
@article{osti_22365065,
title = {Formation, tidal evolution, and habitability of the Kepler-186 system},
author = {Bolmont, Emeline and Raymond, Sean N. and Selsis, Franck and Hersant, Franck and Von Paris, Philip and Quintana, Elisa V. and Barclay, Thomas, E-mail: bolmont@obs.u-bordeaux1.fr},
abstractNote = {The Kepler-186 system consists of five planets orbiting an early M dwarf. The planets have physical radii of 1.0-1.50 R {sub ⊕} and orbital periods of 4-130 days. The 1.1 R {sub ⊕} Kepler-186f with a period of 130 days is of particular interest. Its insolation of roughly 0.32 S {sub ⊕} places it within the surface liquid water habitable zone (HZ). We present a multifaceted study of the Kepler-186 system, using two sets of parameters which are consistent with the data and also self-consistent. First, we show that the distribution of planet masses can be roughly reproduced if the planets were accreted from a high surface density disk presumably sculpted by an earlier phase of migration. However, our simulations predict the existence of one to two undetected planets between planets e and f. Next, we present a dynamical analysis of the system including the effect of tides. The timescale for tidal evolution is short enough that the four inner planets must have small obliquities and near-synchronous rotation rates. The tidal evolution of Kepler-186f is slow enough that its current spin state depends on a combination of its initial spin state, its dissipation rate, and the stellar age. Finally, we study the habitability of Kepler-186f with a one-dimensional climate model. The planet's surface temperature can be raised above 273 K with 0.5-5 bars of CO{sub 2}, depending on the amount of N{sub 2} present. Kepler-186f represents a case study of an Earth-sized planet in the cooler regions of the HZ of a cool star.},
doi = {10.1088/0004-637X/793/1/3},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 793,
place = {United States},
year = {2014},
month = {9}
}