The formation of brown dwarfs as revealed by the mass function of IC 2391 [Elektronische Ressource] / presented by Steve Boudreault

The formation of brown dwarfsas revealed by the massfunction of IC 2391Steve BoudreaultMax-Planck-Institut fu¨r AstronomieHeidelberg 2008Dissertation in Astronomysubmitted to theCombined Faculties for the Natural Sciences and for Mathematicsof the Ruperto-Carola University of Heidelberg, Germany.for the degree ofDoctor of Natural Sciencespresented byDipl.-Astron. Steve Boudreaultˆborn in Sept-Iles, CanadaOral examination: 20.11.2008, 14:00pmThe formation of brown dwarfsas revealed by the massfunction of IC 2391Referees: Prof. Dr. Ralf S. KlessenDr. Coryn A.L. Bailer-JonesiAbstractThis PhD thesis deals with the formation and evolution of brown dwarfs. Here, we presentthe stellar and substellar mass function of the open cluster IC 2391, plus its radial de-pendence, and use this to put constraints on the formation mechanism of brown dwarfs.Our multiband optical and infrared photometric survey with spectroscopic follow up cov-ers 11 square degrees, making it the largest survey of this cluster to date. We observethat there is no variation in the mass function over the stellar/substellar boundary at allthree cluster radius intervals analyzed. From this lack of discontinuity, we conclude thatthe stellar embryo ejection mechanism cannot be the unique brown dwarf formation pathif this formation mechanism produces a higher velocity dispersion for brown dwarfs thanthe stars obtain.