The surface brightness–colour relations based on eclipsing binary stars and calibrated withGaiaEDR3

Abstract

Aims. The surface brightness–colour relation (SBCR) is a basic tool for establishing precise and accurate distances within the Local Group. Detached eclipsing binary stars with accurately determined radii and trigonometric parallaxes allow calibration of the SBCRs with unprecedented accuracy. Methods. 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. Results. The resulting SBCRs cover stellar spectral types from B9 V to G7 V. For calibrations, we used Johnson optical B and V, Gaia GBP and G, and 2MASS JHK bands. The most precise relations are calibrated using the infrared K band and allow angular diameters of A-, F-, and G-type dwarf and subgiant stars to be predicted with a precision of 1%.

Current Challenges in Cepheid Distance Calibrations Using Gaia EDR3

“…Breuval et al (2021) derive a metallicity dependence using the Magellanic Clouds Cepheids in combination with EDR3 data for Galactic Cepheids, without the need for any additional offset. Graczyk et al (2021) also calibrate the surface-brightness/color relations of bright detached eclipsing binaries (5.5 < G < 12 mag) in the color range 1.45 < ν eff < 1.75, also without invoking an additional parallax offset.…”

Space-Based Photometry of Binary Stars: From Voyager to TESS

“…There are many other well-known EBs for which precise results have been obtained from TESS data. AL Dor and BN Scl were studied by Graczyk et al [260] as part of a systematic recalibration of the surface brightness relations for dwarf stars. HS Hya used to show eclipses that were deeper than 0.5 mag in the 1970s (Gyldenkerne et al [261]), around 0.05 mag deep in the 2000s (Zasche and Paschke [262]), and are now on the verge of disappearing entirely (Davenport et al [263]).…”

Space-Based Photometry Of Binary Stars: From Voyager To TESS

“…There are many other well-known EBs for which precise results have been obtained from TESS data. AL Dor and BN Scl were studied by Graczyk et al [260] as part of a systematic recalibration of the surface brightness relations for dwarf stars. HS Hya used to show eclipses that were deeper than 0.5 mag in the 1970s (Gyldenkerne et al [261]), around 0.05 mag deep in the 2000s (Zasche & Paschke [262]), and are now on the verge of disappearing entirely (Davenport et al [263]).…”