Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes

• Published in: The Astronomical journal Vol. 153; no. 3; p. 136
• Main Authors: Stassun, Keivan G., Collins, Karen A., Gaudi, B. Scott
• Format: Journal Article
• Language: English
• Published: United States The American Astronomical Society 01.03.2017
• Subjects: Accuracy; astronomical databases: miscellaneous; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; DATA ANALYSIS; Empirical analysis; Fluxes; MASS; methods: data analysis; PLANETS; planets and satellites: fundamental parameters; RADIAL VELOCITY; SATELLITES; STARS; stars: fundamental parameters; Transit; Uncertainty
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/1538-3881/aa5df3

We present empirical measurements of the radii of 116 stars that host transiting planets. These radii are determined using only direct observables-the bolometric flux at Earth, the effective temperature, and the parallax provided by the Gaia first data release-and thus are virtually model independent, with extinction being the only free parameter. We also determine each star's mass using our newly determined radius and the stellar density, a virtually model independent quantity itself from previously published transit analyses. These stellar radii and masses are in turn used to redetermine the transiting-planet radii and masses, again using only direct observables. The median uncertainties on the stellar radii and masses are 8% and 30%, respectively, and the resulting uncertainties on the planet radii and masses are 9% and 22%, respectively. These accuracies are generally larger than previously published model-dependent precisions of 5% and 6% on the planet radii and masses, respectively, but the newly determined values are purely empirical. We additionally report radii for 242 stars hosting radial-velocity (non-transiting) planets, with a median achieved accuracy of 2%. Using our empirical stellar masses we verify that the majority of putative "retired A stars" in the sample are indeed more massive than ∼1.2 . Most importantly, the bolometric fluxes and angular radii reported here for a total of 498 planet host stars-with median accuracies of 1.7% and 1.8%, respectively-serve as a fundamental data set to permit the re-determination of transiting-planet radii and masses with the Gaia second data release to 3% and 5% accuracy, better than currently published precisions, and determined in an entirely empirical fashion.