Fundamental parameters and infrared excesses of Tycho-Gaia stars

Effective temperatures and luminosities are calculated for 1475 921 Tycho-2 and 107 145 Hipparcos stars, based on distances from Gaia Data Release 1. Parameters are derived by comparing multi-wavelength archival photometry to BT-SETTL model atmospheres. The 1 sigma uncertainties for the Tycho-2 and Hipparcos stars are +/- 137 and +/- 125 K in temperature and +/- 35 and +/- 19 per cent in luminosity. The luminosity uncertainty is dominated by that of the Gaia parallax. Evidence for infrared excess between 4.6 and 25 mu m is found for 4256 stars, of which 1883 are strong candidates. These include asymptotic giant branch (AGB) stars, Cepheids, Herbig Ae/Be stars, young stellar objects and other sources. We briefly demonstrate the capabilities of this data set by exploring local interstellar extinction, the onset of dust production in AGB stars, the age and metallicity gradients of the solar neighbourhood and structure within the Gould Belt. We close by discussing the potential impact of future Gaia data releases.