The surface brightness - colour relations based on eclipsing binary stars and calibrated with Gaia EDR3

TL;DR

This paper calibrates the surface brightness-color relation using eclipsing binary stars and Gaia EDR3 data, achieving high precision in stellar distance measurements across various spectral types.

Contribution

It provides a highly accurate calibration of SBCRs for late F to G-type stars using eclipsing binaries and Gaia parallaxes, extending previous relations with unprecedented precision.

Findings

SBCRs calibrated for spectral types B9 V to G7 V

Infrared K band calibration predicts stellar diameters with 1% accuracy

Combined data from 28 eclipsing binaries for robust calibration

Abstract

The surface brightness -- colour relation (SBCR) is a basic tool in establishing precise and accurate distances within the Local Group. Detached eclipsing binary stars with accurately determined radii and trigonometric parallaxes allow for a calibration of the SBCRs with unprecedented accuracy. We analysed four nearby eclipsing binary stars containing late F-type main sequence components: AL Ari, AL Dor, FM Leo and BN Scl. We determined very precise spectroscopic orbits and combined them with high precision ground- and space-based photometry. We derived the astrophysical parameters of their components with mean errors of 0.1% for mass and 0.4% for radius. We combined those four systems with another 24 nearby eclipsing binaries with accurately known radii from the literature for which $Gaia$ EDR3 parallaxes are available, in order to derive the SBCRs. The resulting SBCRs cover stellar spectral types from B9 V to G7 V. For calibrations we used Johnson optical $B$ and $V$, $Gaia$ $G_{\rm BP}$ and $G$ and 2MASS $JHK$ bands. The most precise relations are calibrated using the infrared $K$ band and allow to predict angular diameters of A-, F-, and G-type dwarf and subgiant stars with a precision of 1%.