On the use of Gaia magnitudes and new tables of bolometric corrections

TL;DR

This paper provides new synthetic Gaia photometry and bolometric corrections based on the MARCS grid, addressing calibration issues and enabling improved stellar luminosity estimates from Gaia data.

Contribution

It introduces a comprehensive set of Gaia synthetic magnitudes and bolometric corrections, along with interpolation routines and extinction coefficients, enhancing stellar parameter determinations.

Findings

Detection of a magnitude-dependent offset in Gaia DR2 G magnitudes

Validation of synthetic colours against space-borne spectrophotometry

Provision of Teff-dependent extinction coefficients

Abstract

The availability of reliable bolometric corrections and reddening estimates, rather than the quality of parallaxes will be one of the main limiting factors in determining the luminosities of a large fraction of Gaia stars. With this goal in mind, we provide Gaia G, BP and RP synthetic photometry for the entire MARCS grid, and test the performance of our synthetic colours and bolometric corrections against space-borne absolute spectrophotometry. We find indication of a magnitude-dependent offset in Gaia DR2 G magnitudes, which must be taken into account in high accuracy investigations. Our interpolation routines are easily used to derive bolometric corrections at desired stellar parameters, and to explore the dependence of Gaia photometry on Teff, log(g), [Fe/H], alpha-enhancement and E(B-V). Gaia colours for the Sun and Vega, and Teff-dependent extinction coefficients, are also provided.