Archival period study of the eclipsing binary KT Hydrae

Abstract

We have undertaken an archival survey of the photographic-plate collections of Harvard College Observatory to search for times of minima of the eclipsing binary KT Hydrae. We report here on the result of that survey, which includes an improved determination of the system's period (3<SUP>d</SUP>.387041 ± 0<SUP>d</SUP>.00001). A new finding is that the period of KT Hydrae has been variable over the past century. We have also obtained a spectral classification for the variable (mid to late A), and we compare KT Hydrae to other similar eclipsing binary systems.