Asteroseismic versus Gaia distances: A first comparison

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-invariables 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.J.D.R. and C.A. gratefully acknowledge the support from the Belgian Federal Science Policy Office (Belspo, Gaia-DPAC) and from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 670519: MAMSIE). G.M. gratefully acknowledges support from IAP research Network P7/06 of the Belgian Government (Belgian Science Policy). This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research made use of the SIMBAD database and the VizieR catalogue access tool, operated at CDS, Strasbourg, France, and of the SAO/NASA Astrophysics Data System.asteroseismology; stars: fundamental parameters; stars: oscillations; astronomical databases: miscellaneous; parallaxes; Galaxy: structur