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Kepler-167e as a Probe of the Formation Histories of Cold Giants with Inner Super-Earths

Chachan, Yayaati and Dalba, Paul A. and Knutson, Heather A. and Fulton, Benjamin J. and Thorngren, Daniel and Beichman, Charles and Ciardi, David R. and Howard, Andrew W. and Van Zandt, Judah (2022) Kepler-167e as a Probe of the Formation Histories of Cold Giants with Inner Super-Earths. Astrophysical Journal, 926 (1). Art. No. 62. ISSN 0004-637X. doi:10.3847/1538-4357/ac3ed6.

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The observed correlation between outer giant planets and inner super-Earths is emerging as an important constraint on planet formation theories. In this study, we focus on Kepler-167, which is currently the only system known to contain both inner transiting super-Earths and a confirmed outer transiting gas giant companion beyond 1 au. Using long-term radial velocity monitoring, we measure the mass of the gas giant Kepler-167e (P = 1071 days) to be 1.01^(+0.16)_(−0.15) M_J, thus confirming it as a Jupiter analog. We refit the Kepler photometry to obtain updated radii for all four planets. Using a planetary structure model, we estimate that Kepler-167e contains 66 ± 19 M⊕ of solids and is significantly enriched in metals relative to its solar-metallicity host star. We use these new constraints to explore the broader question of how systems like Kepler-167 form in the pebble accretion framework for giant planet core formation. We utilize simple disk evolution models to demonstrate that more massive and metal-rich disks, which are the most favorable sites for giant planet formation, can also deliver enough solids to the inner disk to form systems of super-Earths. We use these same models to constrain the nature of Kepler-167's protoplanetary disk and find that it likely contained ≳300 M⊕ of dust and was ≳40 au in size. These values overlap with the upper end of the observed dust mass and size distributions of Class 0 and I disks and are also consistent with the observed occurrence rate of Jupiter analogs around Sun-like stars.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Chachan, Yayaati0000-0003-1728-8269
Dalba, Paul A.0000-0002-4297-5506
Knutson, Heather A.0000-0002-0822-3095
Fulton, Benjamin J.0000-0003-3504-5316
Thorngren, Daniel0000-0002-5113-8558
Beichman, Charles0000-0002-5627-5471
Ciardi, David R.0000-0002-5741-3047
Howard, Andrew W.0000-0001-8638-0320
Van Zandt, Judah0000-0002-4290-6826
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 August 25; revised 2021 November 22; accepted 2021 November 29; published 2022 February 11. We are grateful to the referee for a timely, thoughtful, and instructive report that helped improve this paper. The authors would like to express their gratitude to Dan Foreman-Mackey for assistance with the exoplanet package. Y.C. is grateful to Michael Greklek-McKeon, Michiel Lambrechts, Eve Lee, Lee Rosenthal, and Shreyas Vissapragada for helpful discussions. The authors thank all of the observers in the California Planet Search team for their many hours of hard work. H.K. acknowledges support from NSF CAREER grant 1555095. P.D. is supported by a National Science Foundation (NSF) Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via 10.17909/T9059R. Funding for the Kepler mission is provided by the NASA Science Mission Directorate. The STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. Some of 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 NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Finally, the authors recognize and acknowledge the cultural role and reverence that the summit of Maunakea has within the indigenous Hawaiian community. We are deeply grateful to have the opportunity to conduct observations from this mountain. Facilities: Keck:I (HIRES) - , Kepler - . Software: EXOFASTv2 (Eastman et al. 2013, 2019), lightkurve (Lightkurve Collaboration et al. 2018), SpecMatch (Petigura 2015; Petigura et al. 2017), SpecMatch--Emp (Yee et al. 2017), exoplanet (Foreman-Mackey et al. 2021), pymc3 (Salvatier et al. 2016), theano (Theano Development Team et al. 2016), starry (Luger et al. 2019; Agol et al. 2020), celerite (Foreman-Mackey et al. 2017; Foreman-Mackey 2018), astropy (Astropy Collaboration et al. 2018), twopoppy (Birnstiel et al. 2012).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NSF Astronomy and Astrophysics FellowshipAST-1903811
NASANAS 5-26555
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Planet formation; Super Earths; Extrasolar gaseous giant planets; Radial velocity; Protoplanetary disks
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Planet formation (1241); Super Earths (1655); Extrasolar gaseous giant planets (509); Radial velocity (1332); Protoplanetary disks (1300)
Record Number:CaltechAUTHORS:20220113-234524711
Persistent URL:
Official Citation:Yayaati Chachan et al 2022 ApJ 926 62
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112894
Deposited By: George Porter
Deposited On:14 Jan 2022 17:36
Last Modified:17 Feb 2022 17:35

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