A Be-shell star rotating at the critical limit and a partially stripped companion in a post-mass-transfer solution for the eclipsing binary V505 Mon

In this study of the eclipsing shell star binary HD 48914 (V505 Mon) existing photometric and radial velocity data have been completed by an unbiased determination of the surface temperature of the companion star and new data from the TESS mission. For the mean effective temperatures in our equatorial view, polar/equatorial radii and masses we get about 16000 K (dimmed), 4.27 / 6.37 Rsun and 7.40 Msun for the Be star, and about 14400 K, 6.19 / 7.17 Rsun and 2.03 Msun for the companion star (a contracting hot subdwarf precursor). Their calculated rotational equatorial velocities both are surprisingly high: 467 km/s for the Be star rotating at its centrifugal limit as well as 131 km/s for its former donor star companion. The Be star is surrounded by a large equatorial decretion disk having a radius of about 65 Rsun and fits into the main sequence of stellar models at a sub-solar metallicity of Z = 0.006.