The Masses of the B Stars in the High Galactic Latitude Eclipsing Binary IT Librae11Based on observations made at the 2.1 m Otto Struve Telescope of McDonald Observatory operated by the University of Texas at Austin and also at the 2.1 m telescope at Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities

Abstract

ABSTRACTA number of blue stars that appear to be similar to Population I B stars in the star‐forming regions of the Galactic disk are found more than 1 kpc from the Galactic plane. Uncertainties about the true distances and masses of these high‐latitude B stars have fueled a debate as to their origin and evolutionary status. The eclipsing binary IT Lib is composed of two B stars, is approximately 1 kpc above the Galactic plane, and is moving back toward the plane. Observations of the light and velocity curves presented here lead to the conclusion that the B stars in this system are massive young main‐sequence stars. While there are several possible explanations, it appears most plausible that the IT Lib system formed in the disk about 30 million years ago and was ejected on a trajectory taking it to its present position.