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The California Legacy Survey. III. On the Shoulders of (Some) Giants: The Relationship between Inner Small Planets and Outer Massive Planets

Rosenthal, Lee J. and Knutson, Heather A. and Chachan, Yayaati and Dai, Fei and Howard, Andrew W. and Fulton, Benjamin J. and Chontos, Ashley and Crepp, Justin R. and Dalba, Paul A. and Henry, Gregory W. and Kane, Stephen R. and Petigura, Erik A. and Weiss, Lauren M. and Wright, Jason T. (2022) The California Legacy Survey. III. On the Shoulders of (Some) Giants: The Relationship between Inner Small Planets and Outer Massive Planets. Astrophysical Journal Supplement Series, 262 (1). Art. No. 1. ISSN 0067-0049. doi:10.3847/1538-4365/ac7230.

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We use a high-precision radial velocity survey of FGKM stars to study the conditional occurrence of two classes of planets: close-in small planets (0.023–1 au, 2–30 M_⊕) and distant giant planets (0.23–10 au, 30–6000 M_⊕). We find that 41_(-13)^(+15)% of systems with a close-in, small planet also host an outer giant, compared to 17.6_(-1.9)^(+2.4)% for stars irrespective of small planet presence. This implies that small planet hosts may be enhanced in outer giant occurrences compared to all stars with 1.7σ significance. Conversely, we estimate that 42₋₁₃⁺¹⁷% of cold giant hosts also host an inner small planet, compared to 27.6_(-4.8)^(+5.8)% of stars irrespective of cold giant presence. We also find that more massive and close-in giant planets are not associated with small inner planets. Specifically, our sample indicates that small planets are less likely to have outer giant companions more massive than approximately 120 M_⊕ and within 0.3–3 au, than to have less massive or more distant giant companions, with ∼2.2σ confidence. This implies that massive gas giants within 0.3–3 au may suppress inner small planet formation. Additionally, we compare the host-star metallicity distributions for systems with only small planets and those with both small planets and cold giants. In agreement with previous studies, we find that stars in our survey that only host small planets have a metallicity distribution that is consistent with the broader solar-metallicity-median sample, while stars that host both small planets and gas giants are distinctly metal rich with ∼2.3σ confidence.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemCode ItemCode
Rosenthal, Lee J.0000-0001-8391-5182
Knutson, Heather A.0000-0002-5375-4725
Chachan, Yayaati0000-0003-1728-8269
Dai, Fei0000-0002-8958-0683
Howard, Andrew W.0000-0001-8638-0320
Fulton, Benjamin J.0000-0003-3504-5316
Chontos, Ashley0000-0003-1125-2564
Crepp, Justin R.0000-0003-0800-0593
Dalba, Paul A.0000-0002-4297-5506
Henry, Gregory W.0000-0003-4155-8513
Kane, Stephen R.0000-0002-7084-0529
Petigura, Erik A.0000-0003-0967-2893
Weiss, Lauren M.0000-0002-3725-3058
Wright, Jason T.0000-0001-6160-5888
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 20; revised 2022 May 9; accepted 2022 May 20; published 2022 August 17. L.J.R. led the construction of this paper, including performing all analysis, generating all of the figures, and writing this manuscript. Y.C., F.D., H.A.K., and A.W.H. advised substantially on the scientific direction of this work. All other coauthors contributed feedback on this manuscript and analysis therein. We thank the anonymous reviewer for constructive feedback on our analysis, particularly regarding the details and pitfalls of measuring planet occurrence. We thank Ken and Gloria Levy, who supported the construction of the Levy Spectrometer on the Automated Planet Finder, which was used heavily for this research. We thank the University of California and Google for supporting Lick Observatory, and the UCO staff as well as UCO director Claire Max for their dedicated work scheduling and operating the telescopes of Lick Observatory. A.C. acknowledges support from the National Science Foundation through the Graduate Research Fellowship Program (DGE 1842402). G.W.H. acknowledges long-term support from NASA, NSF, Tennessee State University, and the State of Tennessee through its Centers of Excellence program. A.W.H. acknowledges NSF grant 1753582. H.A.K. acknowledges NSF grant 1555095. P.D. gratefully acknowledges support from a National Science Foundation (NSF) Astronomy & Astrophysics Postdoctoral Fellowship under award AST-1903811. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Software: All code used in this paper is available at and This research makes use of GNU Parallel (Tange 2011). We made use of the following publicly available Python modules: astropy (Astropy Collaboration et al. 2013), matplotlib (Hunter 2007), numpy/scipy (van der Walt et al. 2011), pandas (McKinney 2010), emcee (Foreman-Mackey et al. 2013), and RadVel (Fulton et al. 2018).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Ken and Gloria LevyUNSPECIFIED
University of CaliforniaUNSPECIFIED
NSF Graduate Research FellowshipDGE-1842402
Tennessee State UniversityUNSPECIFIED
State of Tennessee Centers of Excellence programUNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-1903811
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Exoplanets
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanets (498)
Record Number:CaltechAUTHORS:20220817-897387000
Persistent URL:
Official Citation:Lee J. Rosenthal et al 2022 ApJS 262 1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116351
Deposited By: George Porter
Deposited On:18 Aug 2022 18:30
Last Modified:18 Aug 2022 18:30

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