Slowly-rotating nitrogen-rich O stars in 30 Doradus
14th Hellenic Astronomy Conference
8-11 July 2019, Volos, Greece
Surface nitrogen enrichment in O-type stars is predicted from evolutionary models for high rotational velocities, as a result of the rotational mixing of CNO-processed material from the core. The VLT/FLAMES Tarantula Survey discovered a group of slowly-rotating nitrogen-rich O-type stars that challenge these predictions. In this poster I will present the preliminary results of a detailed atmosphere analysis of a representative subset of these stars. The derived stellar parameters and surface abundances of carbon, nitrogen, and oxygen can help to provide clues to the nature of these stars, and help improve evolutionary models.