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Astrophysical Insights into Radial Velocity Jitter from an Analysis of 600 Planet-search Stars

Luhn, Jacob K. and Wright, Jason T. and Howard, Andrew W. and Isaacson, Howard (2020) Astrophysical Insights into Radial Velocity Jitter from an Analysis of 600 Planet-search Stars. Astronomical Journal, 159 (5). Art. No. 235. ISSN 1538-3881. https://resolver.caltech.edu/CaltechAUTHORS:20200519-123744257

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Abstract

Radial velocity (RV) detection of planets is hampered by astrophysical processes on the surfaces of stars that induce a stochastic signal, or "jitter," which can drown out or even mimic planetary signals. Here, we empirically and carefully measure the RV jitter of more than 600 stars from the California Planet Search sample on a star by star basis. As part of this process, we explore the activity–RV correlation of stellar cycles and include appendices listing every ostensibly companion-induced signal we removed and every activity cycle we noted. We then use precise stellar properties from Brewer et al. to separate the sample into bins of stellar mass and examine trends with activity and with evolutionary state. We find that RV jitter tracks stellar evolution and that in general, stars evolve through different stages of RV jitter: the jitter in younger stars is driven by magnetic activity, while the jitter in older stars is convectively driven and dominated by granulation and oscillations. We identify the "jitter minimum"—where activity-driven and convectively driven jitter have similar amplitudes—for stars between 0.7 and 1.7 M⊙ and find that more-massive stars reach this jitter minimum later in their lifetime, in the subgiant or even giant phases. Finally, we comment on how these results can inform future RV efforts, from prioritization of follow-up targets from transit surveys like TESS to target selection of future RV surveys.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-3881/ab855aDOIArticle
https://arxiv.org/abs/2004.13734arXivDiscussion Paper
ORCID:
AuthorORCID
Luhn, Jacob K.0000-0002-4927-9925
Wright, Jason T.0000-0001-6160-5888
Howard, Andrew W.0000-0001-8638-0320
Isaacson, Howard0000-0002-0531-1073
Additional Information:© 2020 The American Astronomical Society. Received 2019 October 23; revised 2020 March 2; accepted 2020 March 3; published 2020 April 27. The authors thank Fabienne Bastien for her founding role in initiating the investigation and defining the project. Her insight, discussions, and advice have greatly contributed to this work. We thank John Brewer for many useful discussions and clarifications regarding spectroscopic stellar properties. We thank John Johnson for the use of data on HD 142091. We thank Raphaëlle Haywood and Tim Milbourne for their discussion on solar granulation and the HARPS data. We thank Sharon Wang for helpful discussions regarding solar oscillations. Finally, we thank the referee, whose suggestions have helped clarify and focus the work presented here. 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 always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Keck time for this project has been awarded from many sources, primarily institutional time from the University of California, Caltech, NASA, and Yale. We thank the many observers and CPS team members who have worked over the decades to produce this invaluable data set. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France; the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org.; and of NASA's Astrophysics Data System Bibliographic Services. This work was partially supported by funding from the Center for Exoplanets and Habitable Worlds, which is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE1255832.
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Center for Exoplanets and Habitable WorldsUNSPECIFIED
Pennsylvania State UniversityUNSPECIFIED
Eberly College of ScienceUNSPECIFIED
Pennsylvania Space Grant ConsortiumUNSPECIFIED
NSF Graduate Research FellowshipDGE-1255832
Subject Keywords:Radial velocity ; Exoplanet astronomy ; Stellar astronomy ; Stellar phenomena ; Exoplanet detection methods
Issue or Number:5
Classification Code:Unified Astronomy Thesaurus concepts: Radial velocity (1332); Exoplanet astronomy (486); Stellar astronomy (1583); Stellar phenomena (1619); Exoplanet detection methods (489)
Record Number:CaltechAUTHORS:20200519-123744257
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200519-123744257
Official Citation:Jacob K. Luhn et al 2020 AJ 159 235
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103316
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 May 2020 19:54
Last Modified:19 May 2020 19:54

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