Larger planet radii inferred from stellar "flicker" brightness variations of bright planet-host stars

Fabienne A. Bastien, Keivan G. Stassun, Joshua Pepper

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure log g to a high accuracy of 0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

Original languageEnglish (US)
Article numberL9
JournalAstrophysical Journal Letters
Volume788
Issue number1
DOIs
StatePublished - Jun 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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