The Mass-Temperature Relation for B and Early A Stars Based on IUE Spectra of Detached Eclipsing Binaries

Abstract

Ultraviolet spectra were taken of 25 Detached Eclipsing Binaries (DEBs) with spectral types O, B, and early A with the International Ultraviolet Explorer (IUE) satellite in the 1150 to 1900 ${\AA}$ region. The spectra were compared with BOSZ model atmospheres (Bohlin, et al. 2017). The composite spectra of the DEBs were modeled by a combination of models representing the hot and cool components, and the temperatures of the hottest components of the systems were determined. From these temperatures a direct Mass-Temperature relation was obtained for stars close to the main sequence with solar metallicity for B and early A stars: log M/Msun = -5.90 $\pm$ 0.27 + (1.56 $\pm$ 0.07) x log T This relation allows a mass to be inferred for comparable stars from an ultraviolet spectrum. The five chemically peculiar Am stars in the sample have larger radii than normal A stars of the same mass.