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Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc

Hirsch, Lea A. and Rosenthal, Lee and Fulton, Benjamin J. and Howard, Andrew W. and Ciardi, David R. and Marcy, Geoffrey W. and Nielsen, Eric and Petigura, Erik A. and de Rosa, Robert J. and Isaacson, Howard and Weiss, Lauren M. and Sinukoff, Evan and Macintosh, Bruce (2021) Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc. Astronomical Journal, 161 (3). Art. No. 134. ISSN 0004-6256. doi:10.3847/1538-3881/abd639.

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We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25 pc. Using adaptive optics imaging observations from the Lick 3 m and Palomar 200" Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single- and multiple-star systems. We found that planets with masses in the range of 0.1–10 M_J and with semimajor axes of 0.1–10 au have an occurrence rate of 0.18^(+0.04)_(−0.03) planets per star when they orbit single stars and an occurrence rate of 0.12 ± 0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation <100 au, and none had a separation <50 au. These numbers yielded planet occurrence rates of 0.20^(+0.07)_(−0.06) planets per star for binaries with separation a_B > 100 au and 0.04^(+0.04)_(−0.02) planets per star for binaries with separation a_B < 100 au. The similarity in the planet occurrence rate around single stars and wide primaries implies that wide binary systems should actually host more planets than single-star systems, since they have more potential host stars. We estimated a system-wide planet occurrence rate of 0.3 planets per wide binary system for binaries with separations a_B > 100 au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1 au than inside 1 au by nearly 4σ, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1 au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100 au.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hirsch, Lea A.0000-0001-8058-7443
Rosenthal, Lee0000-0001-8391-5182
Fulton, Benjamin J.0000-0003-3504-5316
Howard, Andrew W.0000-0001-8638-0320
Ciardi, David R.0000-0002-5741-3047
Marcy, Geoffrey W.0000-0002-2909-0113
Nielsen, Eric0000-0001-6975-9056
Petigura, Erik A.0000-0003-0967-2893
de Rosa, Robert J.0000-0002-4918-0247
Isaacson, Howard0000-0002-0531-1073
Weiss, Lauren M.0000-0002-3725-3058
Sinukoff, Evan0000-0002-5658-0601
Macintosh, Bruce0000-0003-1212-7538
Additional Information:© 2021 The American Astronomical Society. Received 2020 June 30; revised 2020 October 19; accepted 2020 December 7; published 2021 February 22. We thank the anonymous reviewer for their thoughtful questions and suggestions, which have helped to improve this manuscript. L.A.H. thanks James Graham for useful discussions and advice on this survey and statistical analysis. The authors 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, as well as the UCO staff and UCO director Claire Max for their dedicated work scheduling and operating the telescopes of Lick Observatory. L.A.H. acknowledges funding support from the National Science Foundation and NASA during the completion of much of this project. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facility: Keck I/HIRES; Automated Planet Finder/Levy Spectrometer; Lick Shane/ShaneAO; Palomar/PHARO. - Software: RadVel (Fulton et al. 2016); RVSearch (L. Rosenthal et al. 2021, in preparation); SpecMatch (Petigura et al. 2017); isoclassify (Huber et al. 2017); PyKLIP (Wang et al. 2015b); photutils (Bradley et al. 2017); astropy (Astropy Collaboration et al. 2013; Price-Whelan et al. 2018); matplotlib (Hunter 2007).
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:Radial velocity; Exoplanet catalogs; Exoplanet formation; Planet hosting stars
Issue or Number:3
Classification Code:Unified Astronomy Thesaurus concepts: Radial velocity (1332); Exoplanet catalogs (488); Exoplanet formation (492); Planet hosting stars (1242)
Record Number:CaltechAUTHORS:20210301-081416249
Persistent URL:
Official Citation:Lea A. Hirsch et al 2021 AJ 161 134
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108239
Deposited By: Tony Diaz
Deposited On:01 Mar 2021 17:40
Last Modified:16 Nov 2021 19:10

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