The Hyades Binaries θ~1 Tauri and θ~2 Tauri: The Distance to the Cluster and the Mass-Luminosity Relation

摘要

We report new spectroscopic observations of the close binaries θ~1 Tauri and θ~2 Tauri in the Hyades. Our radial velocities for the primary component of θ~1Tau, supplemented with other velocities from the literature and existing astrometric information (speckle observations and lunar occultation measurements), have enabled us to solve for an astrometric-spectroscopic orbit giving a period of 16.3 yr and a nearly edge-on configuration on the sky.