Spectroscopy and asteroseismic modelling of the red giant binary system KIC 10841730

Stellar modelling is crucial for understanding the structure and age of stars. The accuracy of a stellar model is limited by the constraints from observations and the theory behind the physical processes. Gravitationally bound stars of a binary system provide an excellent opportunity for a combined study, which provides strong constraints on the stellar models. Due to their shared origin, both stars share the same age and initial chemical composition. Combined with spectroscopy and radial-velocity measurements it is additionally possible to determine the mass ratio. Such a binary system is particularly promising if both stars are oscillating. The detected oscillation modes give valuable insights into the internal structure and evolutionary state of the stars and complement a detailed modelling analysis. KIC 10841730 is a great example of such ideal conditions. The binary system consists of a helium-burning red-giant clump star and a red-giant branch star. Both stars are oscillating and were observed with high-resolution spectrographs. We use this wealth of information to test parameters like the mixing length, mass loss and different methods to account for surface effects and demonstrate the high potential of such systems to study ill-constrained effects in the red-giant phase of evolution.