YBC, a stellar bolometric corrections database with variable extinction coefficients: an application to PARSEC isochrones

We present the \texttt{YBC} database of stellar bolometric corrections (BCs), available at \url{http://stev.oapd.inaf.it/YBC}. We homogenize widely-used theoretical stellar spectral libraries and provide BCs for many popular photometric systems, including the Gaia filters. The database can be easily extended to additional photometric systems and stellar spectral libraries. The web interface allows users to transform their catalogue of theoretical stellar parameters into magnitudes and colours of selected filter sets. The BC tables can be downloaded or also be implemented into large simulation projects using the interpolation code provided with the database. We compute extinction coefficients on a star-by-star basis, hence taking into account the effects of spectral type and non-linearity dependency on the total extinction. We illustrate the use of these BCs in \texttt{PARSEC} isochrones. We show that using spectral-type dependent extinction coefficients is quite necessary for Gaia filters whenever $\Av\gtrsim 0.5$\,mag. BC tables for rotating stars and tables of limb-darkening coefficients are also provided.