title: The formation of brown dwarfs as revealed by the mass function of IC2391
creator: Boudreault, Steve
subject: 520
subject: 520 Astronomy and allied sciences
description: This PhD thesis deals with the formation and evolution of brown dwarfs. Here, we present the stellar and substellar mass function of the open cluster IC2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs. Our multiband optical and infrared photometric survey with spectroscopic follow up covers 11 square degrees, making it the largest survey of this cluster to date. We observe that there is no variation in the mass function over the stellar/substellar boundary at all three cluster radius intervals analyzed.  From this lack of discontinuity, we conclude that the stellar embryo ejection mechanism cannot be the unique brown dwarf formation path if this formation mechanism produces a higher velocity dispersion for brown dwarfs than the stars obtain. Alternatively, the ejection mechanism could be a dominant brown dwarf formation path only if it produces the same velocity dispersion for brown dwarfs as exists for stars in the cluster. In addition, we observe a radial variation in the mass function over the range 0.15 to 0.5Msol. We conclude that this is a signature of mass segregation via dynamical evolution. Analysis of mass functions of other open clusters from different ages and environment, at each side of the stellar/substellar boundary, also indicates that dynamical evolution influences the shape of the mass function.
date: 2008
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/8877/1/thesis_boudreault_2008_uheidelberg.pdf
identifier: DOI:10.11588/heidok.00008877
identifier: urn:nbn:de:bsz:16-opus-88770
identifier:   Boudreault, Steve  (2008) The formation of brown dwarfs as revealed by the mass function of IC2391.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/8877/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng