Solar-like oscillations in the metal-poor subgiant nu Indi: constraining the mass and age using asteroseismology

Abstract

Asteroseismology is a powerful method for determining fundamental properties of stars. We report the first application to a metal-poor object, namely the subgiant star nu Ind. We measured precise velocities from two sites, allowing us to detect oscillations and infer a large frequency separation of Delta_nu = 24.25 +/- 0.25 microHz. Combining this value with the location of the star in the H-R diagram and comparing with standard evolutionary models, we were able to place constraints on the stellar parameters. In particular, our results indicate that nu Ind has a low mass (0.85 +/- 0.04 M_sun) and is at least 9 Gyr old.