TESS Asteroseismology of α Mensae: Benchmark Ages for a G7 Dwarf and its M-dwarf Companion

Ashley Chontos, Daniel Huber, Hans Kjeldsen, Aldo M. Serenelli, Victor Silva Aguirre, Warrick H. Ball, Sarbani Basu, Timothy R. Bedding, William J. Chaplin, Zachary R. Claytor, Enrico Corsaro, Rafael A. García, Steve B. Howell, Mia S. Lundkvist, Savita Mathur, Travis S. Metcalfe, Martin B. Nielsen, Jia Mian Joel Ong, Maïssa Salama, Keivan G. Stassun, R. H. D. Townsend, Jennifer L. van Saders, Mark Winther, R. Paul Butler, C. G. Tinney, Robert A. Wittenmyer

Asteroseismology of bright stars has become increasingly important as a method to determine fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint, and therefore have limited constraints from independent methods such as long-baseline interferometry. Here, we present the discovery of solar-like oscillations in α Men A, a naked-eye (V=5.1) G7 dwarf in TESS's Southern Continuous Viewing Zone. Using a combination of astrometry, spectroscopy, and asteroseismology, we precisely characterize the solar analogue alpha Men A (Teff = 5569 +/- 62 K, R = 0.960 +/- 0.016 Rsun, M = 0.964 +/- 0.045 Msun) as well as its late M-dwarf companion (Teff = 3142 +/- 86 K, R = 0.24 +/- 0.02 Rsun, M = 0.22 +/- 0.02 Msun). Our asteroseismic age of 6.2 +/- 1.4 (stat) +/- 0.6 (sys) Gyr for the primary places α Men B within a small population of M dwarfs with precisely measured ages. We combined multiple ground-based spectroscopy surveys to reveal an activity cycle of 13.1 +/- 1.1 years, a period similar to that observed in the Sun. We used different gyrochronology models with the asteroseismic age to estimate a rotation period of ~30 days for the primary. Alpha Men A is now the closest (d=10pc) solar analogue with a precise asteroseismic age from space-based photometry, making it a prime target for next-generation direct imaging missions searching for true Earth analogues.

https://arxiv.org/abs/2012.10797