Absolute Elements for the Near Contact Eclipsing Binary V878 Herculis

Abstract

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.

Resumen

Hemos modelado simult ́aneamente nuevas curvas de velocidad radial y de luzpara la binaria eclipsante V878 Her con el c ́odigo Wilson-Devinney (WD2003).Se investigaron dos conjuntos de datos distintos para las curvas de luz. Unoproviene del “Transiting Exoplanet Survey Satellite (TESS)” mientras que los otrosse adquirieron en un observatorio terrestre en Canad ́a. Datos espectrosc ́opicos deapoyo se adquirieron con el telescopio Plaskett de 1.83-m en el Dominion Astrophys-ical Observatory (DAO) entre 2009-2020. Se evaluaron los posibles progenitores deesta binaria casi en contacto (NCB) mediante un modelo evolutivo para binariascerradas fr ́ıas. Argumentamos que 878 Her no est ́a en la fase de relajamiento de osci-laciones t ́ermicas (TRO) sino que est ́a justo en proceso de formaci ́on de la binaria encontacto. Su progenitor m ́as probable en la ZAMS tuvo masas de aproximadamente1.7 and 0.6My un per ́ıodo orbital de cerca de 1.6 d ́ıas.