* Astronomy

Title: First Results From The Hertzsprung Song Telescope: Asteroseismology Of The G5 Subgiant Star Mu Her
Author: F. Grundahl, M. Fredslund Andersen, J. Christensen-Dalsgaard, V. Antoci, H. Kjeldsen, R. Handberg, G. Houdek, T. R. Bedding, P. L. Pallé, J. Jessen-Hansen, V. Silva Aguirre, T. R. White, S. Frandsen, S. Albrecht, M. I. Andersen, T. Arentoft, K. Brogaard, W. J. Chaplin, K. Harpsøe, U.G. Jørgensen, I. Karovicova, C. Karoff, P. Kjærgaard Rasmussen, M. N. Lund, M. Sloth Lundkvist, J. Skottfelt, A. Norup Sørensen, R. Tronsgaard, E. Weiss

We report the first asteroseismic results obtained with the Hertzsprung SONG Telescope from an extensive high-precision radial-velocity observing campaign of the subgiant muHerculis. The data set was collected during 215 nights in 2014 and 2015. We detected a total of 49 oscillation modes with l values from 0 to 3, including some l = 1 mixed modes. Based on the rotational splitting observed in l = 1 modes, we determine a rotational period of 52 days and a stellar inclination angle of 63 degrees. The parameters obtained through modelling of the observed oscillation frequencies agree very well with independent observations and imply a stellar mass between 1.11 and 1.15M_sun and an age of 7.8±0.4 Gyr. Furthermore, the high-quality data allowed us to determine the acoustic depths of the He II ionization layer and the base of the convection zone.

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