Retired A Stars and Their Companions VIII: 15 New Planetary Signals Around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts

Creators: Luhn, Jacob K.; Bastien, Fabienne A.; Wright, Jason T.; Johnson, John A.; Howard, Andrew W.; Isaacson, Howard

Abstract

We present the discovery of seven new planets and eight planet candidates around subgiant stars, as additions to the known sample of planets around "retired A stars." Among these are the possible first three-planet systems around subgiant stars, HD 163607 and HD 4917. Additionally, we present calculations of possible transit times, durations, depths, and probabilities for all known planets around subgiant (3 < log g < 4) stars, focused on possible transits during the TESS mission. While most have transit probabilities of 1%–2%, we find that there are three planets with transit probabilities >9%.

Additional Information

© 2019 The American Astronomical Society. Received 2018 May 17; revised 2018 November 1; accepted 2018 November 5; published 2019 March 20. We would like to thank the anonymous referee whose suggestions have greatly enhanced this paper. We would like to thank Thomas Beatty and Arpita Roy for their discussions and helpful comments. Many of the new planets and planet candidates in this work have come to fruition with the last several years of observations. These observations would not have taken place without Andrew Howard shepherding the observations and extending the time baseline for these systems. We also wish to thank Alan Reyes for his help observing. We also wish to thank Scott Gaudi for pointing out that our transit probabilities are a priori transit probabilities and Dan Stevens for clarification on how the a posteriori probabilities would differ. 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. 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 material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE1255832. Software: RVLIN (Wright et al. 2009), BOOTTRAN (Wang et al. 2012), FORECAST (Chen & Kipping 2017).

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Accepted Version - 1811.03043.pdf

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