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primary topic: An observational study of metal-poor stars

An observational study of metal-poor stars
type: Article
abstract: The outer atmosphere of the first generation of low-mass stars retain to a great extent the original composition of the interstellar medium at the time and place of their birth. Hence the earliest phases of Galactical chemical evolution and nucleosynthesis can be investigated by means of studying the old, metal-poor stars. A minority of these stars exhibit dramatic enhancements in their abundances of heavy neutron-capture elements and/or of carbon. The key question for Galactic chemical evolution models is whether these peculiarities reflect the composition of the natal clouds, or if they are due to later (post-birth) mass transfer of chemically processed material from a binary companion. If the latter is the case, these stars should all be members of binary systems. This thesis presents high-resolution elemental-abundance analysis for a sample of 23 very metal-poor (VMP; [Fe=H] < -2.0) stars, 12 of which are extremely metal-poor (EMP; [Fe/H] < -3.0), and 4 of which are ultra metal-poor (UMP; [Fe/H] < -4.0). The results of radial velocity monitoring of 17 r-process enhanced stars (r-I and r-II stars), 24 CEMP-no stars, 18 CEMP-s and four CEMP-r/s stars, are also presented. The stars, for which the abundance analysis were performed, were targeted to explore differences in the abundance ratios of Li, C, N, O, the alpha-elements, the iron-peak elements, and a number of neutron-capture elements. These are elements that constrain the possible astrophysical sites of element production. This sample has substantially increased the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars. The sample of stars include eight that are considered "normal" metal-poor stars, six CEMP-no stars, �ve CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. Lithium is detected for three of the six CEMP-no stars, all of which are Li-depleted with respect to the Li plateau…
date: 2015
author list: authors
type: EPrint
type: DoctoralThesisEPrint
is part of: repository
has document: An observational study of metal-poor stars (Other)
has document: An observational study of metal-poor stars (PDF)
subject: 500 Naturwissenschaften und Mathematik
subject: 520 Astronomie

An observational study of metal-poor stars (PDF)
type: Document
has file: THansen_PhD.pdf
has part: THansen_PhD.pdf

Terese Thidemann Hansen
type: Person
given name: Terese
family name: Thidemann Hansen

An observational study of metal-poor stars (Other)
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An observational study of metal-poor stars (Other)
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An observational study of metal-poor stars (Other)
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An observational study of metal-poor stars (Other)
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An observational study of metal-poor stars (Other)
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primary topic: An observational study of metal-poor stars

500 Naturwissenschaften und Mathematik
type: Concept
preferred label: 500 Natural sciences and mathematics @en

520 Astronomie
type: Concept
preferred label: 520 Astronomy and allied sciences @en