Retired a stars and their companions: Exoplanets orbiting three intermediate-mass subgiants

John Asher Johnson, Debra A. Fischer, Geoffrey W. Marcy, Jason T. Wright, Peter Driscoll, R. Paul Butler, Saskia Hekker, Sabine Reffert, Steven S. Vogt

Research output: Contribution to journalArticle

177 Scopus citations

Abstract

We report precision Doppler measurements of three intermediate-mass subgiants obtained at Lick and Keck Observatories. All three stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. We find a planet with a minimum mass MP sin i = 2.5 MJ in a 351.5 day orbit around HD 192699, a planet with a minimum mass of 2.0 MJin a 341.1 day orbit around HD 210702, and a planet with a minimum mass of 0.61 MJ in a 297.3 day orbit around HD 175541. Mass estimates from stellar interior models indicate that all three stars were formerly A-type, main-sequence dwarfs with masses ranging from 1.65 to 1.85 M. These three long-period planets would not have been detectable during their stars' main-sequence phases due to the large rotational velocities and stellar jitter exhibited by early-type dwarfs. There are now nine "retired" (evolved) A-type stars (M* > 1.6 M ) with known planets. All nine planets orbit at distances a > 0.78 AU, which is significantly different from the semimajor axis distribution of planets around lower mass stars.

Original languageEnglish (US)
Pages (from-to)785-793
Number of pages9
JournalAstrophysical Journal
Volume665
Issue number1 PART 1
DOIs
StatePublished - Aug 10 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Johnson, J. A., Fischer, D. A., Marcy, G. W., Wright, J. T., Driscoll, P., Butler, R. P., Hekker, S., Reffert, S., & Vogt, S. S. (2007). Retired a stars and their companions: Exoplanets orbiting three intermediate-mass subgiants. Astrophysical Journal, 665(1 PART 1), 785-793. https://doi.org/10.1086/519677