Asteroseismic versus Gaia distances: A first comparison

¹ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
e-mail: joris@ster.kuleuven.ac.be
² I-BioStat, Universiteit Hasselt, Martelarenlaan 42, 3500 Hasselt, Belgium
³ I-BioStat, KU Leuven, Kapucijnenvoer 35, 3000 Leuven, Belgium
⁴ Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Versoix, Switzerland
⁵ Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands

Received: 28 September 2016
Accepted: 17 October 2016

Abstract

Context. The Kepler space mission led to a large number of high-precision time series of solar-like oscillators. Using a Bayesian analysis that combines asteroseismic techniques and additional ground-based observations, the mass, radius, luminosity, and distance of these stars can be estimated with good precision. This has given a new impetus to the research field of galactic archeology.

Aims. The first data release of the Gaia space mission contains the Tycho-Gaia Astrometric Solution (TGAS) catalogue with parallax estimates for more than 2 million stars, including many of the Kepler targets. Our goal is to make a first proper comparison of asteroseismic and astrometric parallaxes of a selection of dwarfs, subgiants, and red giants observed by Kepler for which asteroseismic distances were published.

Methods. We compare asteroseismic and astrometric distances of solar-like pulsators using an appropriate statistical errors-in-variables model on a linear and on a logarithmic scale.

Results. For a sample of 22 dwarf and subgiant solar-like oscillators, the TGAS parallaxes considerably improved on the Hipparcos data, yet the excellent agreement between asteroseismic and astrometric distances still holds. For a sample of 938 Kepler pulsating red giants, the TGAS parallaxes are much more uncertain than the asteroseismic ones, making it worthwhile to validate the former with the latter. From errors-in-variables modelling we find a significant discrepancy between the TGAS parallaxes and the asteroseismic values.

Conclusions. For the sample of dwarfs and subgiants, the comparison between astrometric and asteroseismic parallaxes does not require a revision of the stellar models on the basis of TGAS. For the sample of red giants, we identify possible causes of the discrepancy, which we will likely be able to resolve with the more precise Gaia parallaxes in the upcoming releases.