Chemical and kinematic properties of bright metal poor stars

• Main Author: Xu, Weishuang Linda
• Other Authors: Anna Frebel.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2015
• Subjects: Physics.
• Online Access: http://hdl.handle.net/1721.1/100325

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.