The Chromospheric Activity, Age, Metallicty and Space Motions of 36 Wide Binaries

TL;DR

This study investigates chromospheric activity, metallicity, and space motions of wide binary stars, revealing how activity declines with age, and that these binaries exhibit diverse ages and metallicities similar to field stars.

Contribution

First comprehensive analysis linking chromospheric activity, age, metallicity, and kinematics in wide binary systems, expanding understanding beyond cluster stars.

Findings

CA decreases with age from 50 Myr to 8 Gyr.

Little CA change for stars with V-I < 1.0 between 1 Gyr and 5 Gyr.

Wide binaries span a broad range of ages and metallicities, similar to field stars.

Abstract

We present the chromospheric activity (CA) levels, metallicities and full space motions for 41 F, G, K and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries, contain a white dwarf component. In such binaries the total age can be estimated by adding the cooling age of the white dwarf to an estimate of the progenitor's main sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that in general CA decays with age from 50 Myr to at least 8 Gyr for stars with 1.0 < V-I < 2.4. However, little change occurs in CA level for stars with V-I < 1.0 between 1 Gyr and 5 Gyr, consistent with the results of Pace et al. (2009). Our sample also exhibits a negative correlation between stellar age and metallicity, a positive correlation between stellar age and W space velocity component and the W velocity dispersion increases with age. Finally, the population membership of these wide binaries is examined based upon their U, V, W kinematics, metallicity and CA. We conclude that wide binaries are similar to field and cluster stars in these respects. More importantly, they span a much more continuous range in age and metallicity than is afforded by nearby clusters.