ﻻ يوجد ملخص باللغة العربية
Surface brightness-color relations (SBCRs) are used for estimating angular diameters and deriving stellar properties. They are critical to derive extragalactic distances of early-type and late-type eclipsing binaries or, potentially, for extracting planetary parameters of late-type stars hosting planets. Various SBCRs have been implemented so far, but strong discrepancies in terms of precision and accuracy still exist in the literature. We aim to develop a precise SBCR for early-type B and A stars using selection criteria, based on stellar characteristics, and combined with homogeneous interferometric angular diameter measurements. We also improve SBCRs for late-type stars, in particular in the Gaia photometric band. We observed 18 early-type stars with the VEGA interferometric instrument, installed on the CHARA array. We then applied additional criteria on the photometric measurements, together with stellar characteristics diagnostics in order to build the SBCRs. We calibrated a SBCR for subgiant and dwarf early-type stars. The RMS of the relation is $sigma_{F_{V_{0}}} = 0.0051,$mag, leading to an average precision of 2.3% on the estimation of angular diameters, with 3.1% for $V-K < -0.2,$mag and 1.8% for $V-K > -0.2,$mag. We found that the conversion between Johnson-$K$ and 2MASS-$K_s$ photometries is a key issue for early-type stars. Following this result, we have revisited our previous SBCRs for late-type stars by calibrating them with either converted Johnson-$K$ or 2MASS-$K_s$ photometries. We also improve the calibration of these SBCRs based on the Gaia photometry. The expected precision on the angular diameter using our SBCRs for late-type stars ranges from 1.0% to 2.7%. By reaching a precision of 2.3% on the estimation of angular diameters for early-type stars, significant progress has been made to determine extragalactic distances using early-type eclipsing binaries.
Surface brightness-colour relations (SBCRs) are used to derive the stellar angular diameters from photometric observations. They have various astrophysical applications, such as the distance determination of eclipsing binaries or the determination of
The aim of this work is to improve the SBC relation for early-type stars in the $-1 leq V-K leq 0$ color domain, using optical interferometry. Observations of eight B- and A-type stars were secured with the VEGA/CHARA instrument in the visible. The d
The surface brightness - color relationship (SBCR) is a poweful tool for determining the angular diameter of stars from photometry. It was for instance used to derive the distance of eclipsing binaries in the Large Magellanic Cloud (LMC), which led t
[Abridged] Tight correlations between supermassive black hole (SMBH) mass ($M_{rm BH}$) and the properties of the host galaxy have useful implications for our understanding of the growth of SMBHs and evolution of galaxies. Here, we present newly obse
We summarize the properties of the new periodic, small amplitude, variable stars recently discovered in the open cluster NGC 3766. They are located in the region of the Hertzsprung-Russell diagram between delta Sct and slowly pulsating B stars, a reg