An optical study of young stellar clusters [Elektronische Ressource] / put vorward by Da Rio Nicola

An Optical StudyofYoung Stellar ClustersNicola Da RioMax-Planck-Institut fur AstronomieDissertation in Astronomysubmitted to theCombined Faculties of the Natural Sciences and Mathematicsof the Ruperto-Carola-University of Heidelberg, Germanyfor the degree ofDoctor of Natural SciencesPut forward byMaster Phys. Da Rio Nicolaborn in: Udine (Italy)thOral examination: December 13 , 2010An Optical StudyofYoung Stellar ClustersReferees: Prof. Dr. Thomas HenningProf. Dr. Ralf KlessenAbstractIn the first part of this thesis a new analysis of the Orion Nebula Cluster, one of themost studied star-forming regions in the Galaxy, is presented. Based on multi-bandoptical photometry and spectroscopy obtained with the Wide-Field Imager (WFI) at theESO/MPI 2.2-m telescope at La Silla Observatory, I study the systematic effects thatbias the derivation of stellar parameters of pre-main sequence (PMS) stars. I derive thenew H-R diagram of the entire region, and assign masses and ages to all the members.The age is found to be∼ 2−3 Myr, older than previously estimated. I also confirm thepresence of an age spread, and show how the found mass-age correlation canbe affected by the sample incompleteness and uncertainties in the evolutionary models.