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dc.contributor.authorTamblyn, Peter.
dc.creatorTamblyn, Peter.en_US
dc.date.accessioned2011-10-31T18:42:41Z
dc.date.available2011-10-31T18:42:41Z
dc.date.issued1996en_US
dc.identifier.urihttp://hdl.handle.net/10150/187516
dc.description.abstractWe show that extremely luminous, blue stars are present at the Galactic Center (GC) in numbers that are incompatible with normal stellar evolution. Helium 2.058 micrometer images with a spatial resolution of 1 arcsecond show that the helium emission is concentrated on point sources, most of which are bright in the infrared, indicating they are warm and very luminous. Comparison with Monte-Carlo stellar population models demonstrates that normal evolution is incapable of producing this population. Near-infrared spectroscopy at high angular and spectral resolutions has been obtained, along with spectra of an extensive suite of other warm, luminous stars. These spectra provide new constraints on the mass in the central 1/2 parsec and the spectral comparisons confirm the peculiarity of the GC stars. The brightest have few, if any, analogues known in the Galaxy. Constraints from space-based observations on the blue light associated with nuclear populations in nearby galaxies demonstrate that the GC is unique or in a time-dependent phase. We have examined and rejected a number of models expected to produce this density of luminous, blue stars in the central parsec. A possibility remains that they are recently formed massive stars with unusual evolution formed by close binary companions. This model predicts similar populations of peculiar stars only in other dense galactic nuclei which have undergone very recent star formation.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.titleThe peculiar population of helium emission stars at the Galactic Center.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.contributor.chairRieke, George H.en_US
dc.contributor.chairMelia, Fulvioen_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberMcCarthy, Donald W. Jr.en_US
dc.contributor.committeememberPinto, Philipen_US
dc.identifier.proquest9626558en_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2018-08-19T02:14:30Z
html.description.abstractWe show that extremely luminous, blue stars are present at the Galactic Center (GC) in numbers that are incompatible with normal stellar evolution. Helium 2.058 micrometer images with a spatial resolution of 1 arcsecond show that the helium emission is concentrated on point sources, most of which are bright in the infrared, indicating they are warm and very luminous. Comparison with Monte-Carlo stellar population models demonstrates that normal evolution is incapable of producing this population. Near-infrared spectroscopy at high angular and spectral resolutions has been obtained, along with spectra of an extensive suite of other warm, luminous stars. These spectra provide new constraints on the mass in the central 1/2 parsec and the spectral comparisons confirm the peculiarity of the GC stars. The brightest have few, if any, analogues known in the Galaxy. Constraints from space-based observations on the blue light associated with nuclear populations in nearby galaxies demonstrate that the GC is unique or in a time-dependent phase. We have examined and rejected a number of models expected to produce this density of luminous, blue stars in the central parsec. A possibility remains that they are recently formed massive stars with unusual evolution formed by close binary companions. This model predicts similar populations of peculiar stars only in other dense galactic nuclei which have undergone very recent star formation.


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