Spectral Characterization of the Low-mass Companion μ Virgenes B

We report optical and near-infrared spectral characterization of an M dwarf companion to the bright F2 star μ Virgenes. Data from Shane/Kast and IRTF/SpeX yield identical spectral types of M5, and spectral features indicate solar metallicity ([Fe/H] = −0.05 ± 0.20) with no evidence of low surface gravity features at optical or near-infrared bands. Strong Hα emission ( log10LHα/Lbol  = −3.80 ± 0.09) is consistent with an active source at saturation, while the lack of Li i absorption and low surface gravity features constrains the system’s age to ≳200 Myr. Both metallicity and age estimates of the companion are consistent with its primary. As a well-resolved companion to an exceptionally well-characterized bright star, μ Virgenes B serves as a useful benchmark at the transition between partially and fully convective stars.