Astronomy and Astrophysics
Aims: We investigate the solar-like oscillations of the red-giant-branch star γ Cep A, which harbours a giant planet on a wide orbit.
Methods: We did this by utilising both ground-based radial velocities from the SONG network and space-borne photometry from the NASA TESS mission.
Results: From the radial velocities and photometric observations, we created a combined power spectrum, which we used in an asteroseismic analysis to extract individual frequencies. We clearly identify several radial and quadrupole modes as well as multiple mixed, dipole modes. We used these frequencies along with spectroscopic and astrometric constraints to model the star, and we find a mass of 1.27−0.07+0.05 M⊙, a radius of 4.74−0.08+0.07 R⊙, and an age of 5.7−0.9+0.8 Gyr. We then used the mass of γ Cep A and our SONG radial velocities to derive masses for γ Cep B and γ Cep Ab of 0.328−0.012+0.009 M⊙ and 6.6−2.8+2.3 MJup, respectively.
This project aims at the searching, observation and analysis of massive stars in nearby galaxies to provide a solid empirical ground to understand their physical properties as a function of those key parameters that gobern their evolution (i.e. mass, spin, metallicity, mass loss, and binary interaction). Massive stars are central objects to
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary