Persistent Link:
http://hdl.handle.net/10150/184208
Title:
ASYMPTOTIC GIANT BRANCH POPULATIONS IN COMPOSITE STELLAR SYSTEMS.
Author:
COOK, KEM HOLLAND.
Issue Date:
1987
Publisher:
The University of Arizona.
Rights:
Copyright © 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.
Abstract:
This dissertation presents a technique for the identification and classification of late-type stars and for the estimation of M star metallicities. The technique uses broad-band, V and I, CCD images to identify red stars and two intermediate-band CCD images to classify these as carbon or M types. One of the intermediate passbands is centered on a TiO absorption band at 7750Å and the other is centered on a CN absorption band at 8100Å. Color-color plots of V-I versus the intermediate-band index, 77-81, clearly distinguishes carbon from M stars. Observations of both early- and late-type stars were used to define the 77-81 system based upon the intermediate-band filters. The TiO bandstrength deduced from the 77-81 color as a function of V-I color was investigated for field giants and giants in 12 globular clusters. A linear correlation between [Fe/H] and the V-I color at a given TiO bandstrength was found. This correlation can be used to estimate the metallicity of M giants. The stellar population of a field in Baade's Window was examined using this technique. Many late-M stars and no carbon stars were found. The color-color diagram for Baade's Window suggests a range of metallicities for the M giants of [Fe/H] ≈ -0.4 to > +0.2. The stellar population of the Sagittarius Dwarf Irregular galaxy (Sagdig) was examined using the 77-81 system. A method for estimating reddening based upon the color mode of foreground stars was developed for the analysis of the Sagdig data. Sagdig is estimated to be ~ 1.3 megaparsecs distant. Bright blue and red stars in Sagdig are evidence for recent star formation. Carbon stars were identified in Sagdig. They display a bimodal luminosity and color distribution which suggests distinct epochs of star forming activity between 1 and 10 Gyr ago. The spatial distribution of carbon stars and bright red stars in Sagdig shows this galaxy to be much larger than previously thought.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Stars -- Classification.; Stars -- Evolution.; Cool stars -- Classification.; Astronomy -- Observations.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Astronomy; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleASYMPTOTIC GIANT BRANCH POPULATIONS IN COMPOSITE STELLAR SYSTEMS.en_US
dc.creatorCOOK, KEM HOLLAND.en_US
dc.contributor.authorCOOK, KEM HOLLAND.en_US
dc.date.issued1987en_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.description.abstractThis dissertation presents a technique for the identification and classification of late-type stars and for the estimation of M star metallicities. The technique uses broad-band, V and I, CCD images to identify red stars and two intermediate-band CCD images to classify these as carbon or M types. One of the intermediate passbands is centered on a TiO absorption band at 7750Å and the other is centered on a CN absorption band at 8100Å. Color-color plots of V-I versus the intermediate-band index, 77-81, clearly distinguishes carbon from M stars. Observations of both early- and late-type stars were used to define the 77-81 system based upon the intermediate-band filters. The TiO bandstrength deduced from the 77-81 color as a function of V-I color was investigated for field giants and giants in 12 globular clusters. A linear correlation between [Fe/H] and the V-I color at a given TiO bandstrength was found. This correlation can be used to estimate the metallicity of M giants. The stellar population of a field in Baade's Window was examined using this technique. Many late-M stars and no carbon stars were found. The color-color diagram for Baade's Window suggests a range of metallicities for the M giants of [Fe/H] ≈ -0.4 to > +0.2. The stellar population of the Sagittarius Dwarf Irregular galaxy (Sagdig) was examined using the 77-81 system. A method for estimating reddening based upon the color mode of foreground stars was developed for the analysis of the Sagdig data. Sagdig is estimated to be ~ 1.3 megaparsecs distant. Bright blue and red stars in Sagdig are evidence for recent star formation. Carbon stars were identified in Sagdig. They display a bimodal luminosity and color distribution which suggests distinct epochs of star forming activity between 1 and 10 Gyr ago. The spatial distribution of carbon stars and bright red stars in Sagdig shows this galaxy to be much larger than previously thought.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectStars -- Classification.en_US
dc.subjectStars -- Evolution.en_US
dc.subjectCool stars -- Classification.en_US
dc.subjectAstronomy -- Observations.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.proquest8727922en_US
dc.identifier.oclc699819460en_US
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