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

TL;DR

This study derives a direct mass-temperature relation for B and early A stars using ultraviolet spectra from IUE, enabling mass estimation from spectral data and highlighting differences in chemically peculiar Am stars.

Contribution

It provides the first direct empirical mass-temperature relation for B and early A stars based on UV spectra of detached eclipsing binaries.

Findings

Established a mass-temperature relation: log M/Msun = -5.90 ± 0.27 + 1.56 ± 0.07 x log T

Chemically peculiar Am stars have larger radii than normal A stars of the same mass

Ultraviolet spectra can be used to infer stellar masses for similar stars

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.