Absolute Elements for the Near Contact Eclipsing Binary V878 Herculis

This is the authors' abstract. We don't add key points for this paper.

New radial velocity (RV) and light curve (LC) data for the eclipsing binary V878 Her have been simultaneously modeled with the Wilson-Devinney code (WD2003). Two distinct LC datasets were investigated: one was from the Transiting Exoplanet Survey Satellite (TESS) while the others were acquired from a ground-based observatory in Canada. Supporting spectroscopic data were acquired using the 1.83-m Plaskett Telescope at the Dominion Astrophysical Observatory (DAO) between 2009-2020. Potential progenitors of this near contact binary (NCB) were evaluated using an evolutionary model derived from cool close binaries. It is argued that V878 Her is not in the thermal relaxation oscillation (TRO) phase but, instead, it is a first timer, i.e. in a state of contact binary formation. Its most probable ZAMS progenitor had masses equal to about 1.7 and 0.6 M☉ with an orbital period of nearly 1.6 days.