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

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.

published in ApJ

References in corpus (16)

• The Gaia mission
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Search for Associations Containing Young stars (SACY): I. Sample & Searching Method
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• A Stellar Census of the Tucana-Horologium Moving Group
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• Reevaluating the Mass-Radius Relation for Low-Mass, Main Sequence Stars
• BANYAN. V. A Systematic All-Sky Survey for New Very Late-Type Low-Mass Stars and Brown Dwarfs in Nearby Young Moving Groups
• All-sky Co-moving Recovery Of Nearby Young Members. (ACRONYM) II: The Beta Pictoris Moving Group
• A New Method to Identify Nearby, Young, Low-mass Stars
• BANYAN. IX. The Initial Mass Function and Planetary-Mass Object Space Density of the TW Hya Association
• Testing the universality of the IMF with Bayesian statistics: young clusters
• ACRONYM III: Radial Velocities for 336 Candidate Young Low-Mass Stars in the Solar Neighborhood, Including 78 Newly Confirmed Young Moving Group Members
• The Elusive Majority of Young Moving Groups. I. Young Binaries and Lithium-Rich Stars in the Solar Neighborhood
• The Multiplicity of M-Dwarfs in Young Moving Groups
• PSYM-WIDE: a survey for large-separation planetary-mass companions to late spectral type members of young moving groups