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Do Close-in Giant Planets Orbiting Evolved Stars Prefer Eccentric Orbits?

Grunblatt, Samuel K. and Huber, Daniel and Gaidos, Eric and Lopez, Eric D. and Barclay, Thomas and Chontos, Ashley and Sinukoff, Evan and Van Eylen, Vincent and Howard, Andrew W. and Isaacson, Howard (2018) Do Close-in Giant Planets Orbiting Evolved Stars Prefer Eccentric Orbits? Astrophysical Journal Letters, 861 (1). Art. No. L5. ISSN 2041-8213.

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The NASA Kepler and K2 Missions have recently revealed a population of transiting giant planets orbiting moderately evolved, low-luminosity red giant branch stars. Here, we present radial velocity (RV) measurements of three of these systems, revealing significantly non-zero orbital eccentricities in each case. Comparing these systems with the known planet population suggests that close-in giant planets around evolved stars tend to have more eccentric orbits than those around main sequence stars. We interpret this as tentative evidence that the orbits of these planets pass through a transient, moderately eccentric phase where they shrink faster than they circularize due to tides raised on evolved host stars. Additional RV measurements of currently known systems, along with new systems discovered by the recently launched NASA Transiting Exoplanet Survey Satellite (TESS) mission, may constrain the timescale and mass dependence of this process.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Grunblatt, Samuel K.0000-0003-4976-9980
Huber, Daniel0000-0001-8832-4488
Gaidos, Eric0000-0002-5258-6846
Barclay, Thomas0000-0001-7139-2724
Chontos, Ashley0000-0003-1125-2564
Sinukoff, Evan0000-0002-5658-0601
Van Eylen, Vincent0000-0001-5542-8870
Howard, Andrew W.0000-0001-8638-0320
Isaacson, Howard0000-0002-0531-1073
Additional Information:© 2018 The American Astronomical Society. Received 2018 May 7; revised 2018 May 29; accepted 2018 June 6; published 2018 June 27. The authors would like to thank John Livingston, Jim Fuller, Masanobu Kunitomo, Alessandro Brani, Amaury Triaud, Benjamin Pope, Lauren Weiss, Teruyuki Hirano, Travis Berger, Jessica Stasik, Connor Auge, Aaron Do, and Nader Haghighipour for helpful discussions. This research was supported by the NASA K2 Guest Observer Awards NNX16AH45G and NNX17AF76G to D.H. D.H. acknowledges support by the National Aeronautics and Space Administration under Grant NNX14AB92G issued through the Kepler Participating Scientist Program. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer at This work was based on observations at the W. M. Keck Observatory granted by the University of Hawaii, the University of California, and the California Institute of Technology. We thank the observers who contributed to the measurements reported here and acknowledge the efforts of the Keck Observatory staff. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests.
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:planets and satellites: dynamical evolution and stability – planets and satellites: gaseous planets – planet–star interactions
Issue or Number:1
Record Number:CaltechAUTHORS:20180627-102713255
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Official Citation:Samuel K. Grunblatt et al 2018 ApJL 861 L5
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87389
Deposited By: Tony Diaz
Deposited On:27 Jun 2018 17:38
Last Modified:29 Nov 2019 02:48

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