Kepler-1656b: A Dense Sub-Saturn with an Extreme Eccentricity
Abstract
Kepler-1656b is a 5 R⊕ planet with an orbital period of 32 days initially detected by the prime Keplermission. We obtained precision radial velocities of Kepler-1656 with Keck/HIRES in order to confirm the planet and to characterize its mass and orbital eccentricity. With a mass of 48 ± 4 M⊕, Kepler-1656b is more massive than most planets of comparable size. Its high mass implies that a significant fraction, roughly 80%, of the planet's total mass is in high-density material such as rock/iron, with the remaining mass in a low-density H/He envelope. The planet also has a high eccentricity of 0.84 ± 0.01, the largest measured eccentricity for any planet less than 100 M⊕. The planet's high density and high eccentricity may be the result of one or more scattering and merger events during or after the dispersal of the protoplanetary disk.
Additional Information
© 2018 The American Astronomical Society. Received 2018 June 26; revised 2018 July 27; accepted 2018 July 29; published 2018 September 10. We thank Konstantin Batygin for useful discussions, as well as Lauren Weiss and Ian Crossfield for their assistance with Keck/HIRES observations. M.T.B. acknowledges support from a Summer Undergraduate Research Fellowship (SURF) at Caltech, which was funded with the assistance of Hannah Bradley. E.A.P. acknowledges support from a Hubble Fellowship grant HST-HF2-51365.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. for NASA under contract NAS 5-26555. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has long had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Software: Astropy (Astropy Collaboration et al. 2013), batman (Kreidberg 2015), emcee (Foreman-Mackey et al. 2013), Numpy/Scipy (Van Der Walt et al. 2011), Matplotlib (Hunter 2007), Pandas (McKinney 2010), RadVel (Fulton et al. 2018).Attached Files
Published - Brady_2018_AJ_156_147.pdf
Accepted Version - 1809.08436.pdf
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Additional details
- Eprint ID
- 89480
- Resolver ID
- CaltechAUTHORS:20180910-092840714
- Caltech Summer Undergraduate Research Fellowship (SURF)
- HST-HF2-51365.001-A
- NASA Hubble Fellowship
- NAS 5-26555
- NASA
- W. M. Keck Foundation
- Created
-
2018-09-10Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, Division of Geological and Planetary Sciences