Spectroscopy of Massive Stars in the Double Cluster h/chi Persei

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Massive stars are main drivers of the evolution of galaxies because of their energy and momentum input into the interstellar medium through stellar winds and supernovae, and they are important sites of nucleosynthesis. The development of a detailed understanding of their inner structure and evolution is of utmost importance for wide fields of astrophysics. Among many others, evolution models of massive stars provide the basis for the interpretation of stellar populations in star clusters and galaxies. They describe the structure of supernova progenitors and allow chemical yields to be predicted. And, they are the starting point for explaining exotic phenomena such as neutron stars, stellar black holes and some types of gamma-ray bursts.Enormous progress has been made in the modelling of massive star evolution by accounting for the effects of rotation. There is a growing body of evidence that rotation together with mass loss are the physical key ingredients shaping the evolution of massive stars throughout cosmic history. The current models make detailed predictions on the surface properties (stellar parameters and chemical abundances) of massive stars that need to be compared to detailed observations for verification of the assumptions made in the models.A survey of the massive star population in the Galactic double cluster h and chi Persei at high spectral resolution and very high signal-to-noise ratio will be undertaken in order to derive tight observational constraints on stellar evolution models. The homogeneous sample will cover all evolutionary stages from the main sequence over the giant to the supergiant stage in a well-defined environment of unique age and metallicity, comprising slow and fast rotators. Use of sophisticated non-LTE modelling and a novel analysis methodology will provide stellar parameters and chemical abundances at unprecedented accuracy and precision. Surface abundances of the light elements (He, C, N, O) will in particular be used to verify the recently challenged concept of rotational mixing based on a sample of minimised observational bias.We ask for travel money in order to conduct the observing run at Calar Alto Observatory, for which five nights of observing time have been granted with the Echelle spectrograph CAFE on the 2.2m telescope.