TESS asteroseismology of α Mensae: benchmark ages for a G7 dwarf and its M-dwarf companion

Ashley Chontos, Daniel Huber, Travis A. Berger, 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, Zeynep Çelik OrhanSibel Örtel, Maïssa Salama, Keivan G. Stassun, R. H. D. Townsend, Jennifer L. van Saders, Mark Winther, Mutlu Yildiz, R. Paul Butler, C. G. Tinney, Robert A. Wittenmyer

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Asteroseismology of bright stars has become increasingly important as a method to determine the 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 analog α Men A (Teff = 5569 ± 62 K, R = 0.960 ± 0.016 R, M = 0.964 ± 0.045 M). To characterize the fully convective M dwarf companion, we derive empirical relations to estimate mass, radius, and temperature given the absolute Gaia magnitude and metallicity, yielding M = 0.169 ± 0.006 M, R = 0.19 ± 0.01 R, and Teff = 3054 ± 44 K. 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 P = 13.1 ± 1.1 yr for α Men A, 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 = 10 pc) solar analog with a precise asteroseismic age from space-based photometry, making it a prime target for next-generation direct-imaging missions searching for true Earth analogs.
Original languageEnglish
Article number229
Number of pages15
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 1 Dec 2021

Bibliographical note

Accepted to The Astrophysical Journal; 15 pages, 10 figures


  • astro-ph.EP
  • astro-ph.SR


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