ACRONYM IV: Three New, Young, Low-mass Spectroscopic Binaries

TL;DR

This paper reports the discovery and characterization of three new low-mass spectroscopic binaries, two of which are young and associated with nearby moving groups, providing insights into their ages and kinematics.

Contribution

The study identifies three new low-mass spectroscopic binaries and determines their ages and group memberships using high-resolution spectroscopy, including lithium and H-alpha indicators.

Findings

One binary confirmed as Tuc-Hor member, previously undetected.

One binary not associated with known YMG but shows youth indicators.

One binary not part of any known YMG, with strong youth signatures.

Abstract

As part of our search for new low-mass members of nearby young moving groups (YMG), we discovered three low-mass, spectroscopic binaries, two of which are not kinematically associated with any known YMG. Using high-resolution optical spectroscopy, we measure the component and systemic radial velocities of the systems, as well as their lithium absorption and H$\alpha$ emission, both spectroscopic indicators of youth. One system (2MASS J02543316-5108313, M2.0+M3.0) we confirm as a member of the 40 Myr old Tuc-Hor moving group, but whose binarity was previously undetected. The second young binary (2MASS J08355977-3042306, K5.5+M1.5) is not a kinematic match to any known YMG, but each component exhibits lithium absorption and strong and wide H$\alpha$ emission indicative of active accretion, setting an upper age limit of 15 Myr. The third system (2MASS J10260210-4105537, M1.0+M3.0) has been hypothesized in the literature to be a member of the 10 Myr old TW Hya Association (TWA), but with our measured systemic velocity, shows the binary is in fact not part of any known YMG. This last system also has lithium absorption in each component, and has strong and variable H$\alpha$ emission, setting an upper age limit of 15 Myr based on the lithium detection.