Orbits and Dynamical Masses for Six Binary Systems in the Hyades Cluster

TL;DR

This study uses interferometry and radial velocities to measure the masses and orbits of six binary stars in the Hyades, revealing precise masses, testing stellar models, and analyzing stellar activity.

Contribution

It provides the first precise dynamical masses for these binaries, improving the understanding of stellar evolution in the Hyades cluster.

Findings

Masses determined to better than 1% accuracy.

Models overestimate V-band flux by ~0.1 mag for 0.5-1.4 M_sun.

Detected flares and estimated rotation periods from TESS data.

Abstract

We report long baseline interferometric observations with the CHARA Array that resolve six previously known double-lined spectroscopic binary systems in the Hyades cluster, with orbital periods ranging from 3 to 358 days: HD 27483, HD 283882, HD 26874, HD 27149, HD 30676, and HD 28545. We combine those observations with new and existing radial-velocity measurements, to infer the dynamical masses for the components as well as the orbital parallaxes. For most stars the masses are determined to better than 1%. Our work significantly increases the number of systems with mass determinations in the cluster. We find that while current models of stellar evolution for the age and metallicity of the Hyades are able to reproduce the overall shape of the empirical mass-luminosity relation, they overestimate the $V$-band fluxes by about 0.1 mag between 0.5 and 1.4 $M_{\odot}$. The disagreement is smaller in $H$, and near zero in $K$, and depends somewhat on the model. We also make use of the TESS light curves to estimate rotation periods for our targets, and detect numerous flares in one of them (HD 283882), estimating an average flaring rate of 0.44 events per day.