2026-09-19T14:44:32Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1003252022-01-13T07:54:07Zcom_1721.1_7582com_1721.1_7581col_1721.1_131024
Anna Frebel.
Xu, Weishuang Linda
Massachusetts Institute of Technology. Department of Physics.
Massachusetts Institute of Technology. Department of Physics
2015-12-16T16:32:18Z
2015-12-16T16:32:18Z
2015
2015
http://hdl.handle.net/1721.1/100325
930604212
Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-70).
In this work, I analyze the high-resolution spectra of 20 stars, chosen for their low metallicity [Fe/H] </~ -2.5 and proximity to the sun. Using these spectra I model the atmospheres of these stars by determing stellar parameters {Teff, log(g), [mu], [Fe/H]} and obtain also their chemical abundances for 17 elements including Fe, C, Sr, and Ba. Three of these stars are found to possess an overabundance of Carbon relative to Iron. Combining these chemical abundances with those from previously analyzed spectra from the same bright metal-poor star sample, I perform orbit determination and integration on a total of 59 metal-poor stars and extract their kinematic parameters. I also explore how these results depend on the assumed mass of the Milky Way. These chemical and kinematic results are then combined and compared with comparatively metal-rich (-2.5 </~ [Fe/H] </~ 0) samples; a conal distribution of velocity components with respect to metallicity is observed, as well as two distinct populations in eccentricity. The 59 bright metal-poor stars were identified as residing in the inner halo of the Milky Way.
by Weishuang Linda Xu.
S.B.
70 pages
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Physics.
Chemical and kinematic properties of bright metal poor stars
Thesis
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Publication
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<Abstract>In this work, I analyze the high-resolution spectra of 20 stars, chosen for their low metallicity [Fe/H] </~ -2.5 and proximity to the sun. Using these spectra I model the atmospheres of these stars by determing stellar parameters {Teff, log(g), [mu], [Fe/H]} and obtain also their chemical abundances for 17 elements including Fe, C, Sr, and Ba. Three of these stars are found to possess an overabundance of Carbon relative to Iron. Combining these chemical abundances with those from previously analyzed spectra from the same bright metal-poor star sample, I perform orbit determination and integration on a total of 59 metal-poor stars and extract their kinematic parameters. I also explore how these results depend on the assumed mass of the Milky Way. These chemical and kinematic results are then combined and compared with comparatively metal-rich (-2.5 </~ [Fe/H] </~ 0) samples; a conal distribution of velocity components with respect to metallicity is observed, as well as two distinct populations in eccentricity. The 59 bright metal-poor stars were identified as residing in the inner halo of the Milky Way.</Abstract>
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