Harmers, Ilse (2022) Determining Chemical Abundances in CD-51 4628 with iSpec. Bachelor's Thesis, Astronomy.
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Abstract
Nissen and Schuster 2010 analyzed 94 dwarf stars in the solar neighborhood kinematically determined to be Galactic halo stars and concluded that the halo consists of two stellar populations: “high-α” and “low-α” stars. They concluded that the low-α population is most likely accreted from a dwarf galaxy whereas the high-α population belongs to an “in-situ” inner halo population. Differential abundances of α and neutron-capture elements are determined for the low-α halo star CD-51 4628, which is a member of Nissen & Schuster’s sample and was extensively studied at red wavelengths, using high-resolution UVES spectra. The aim of this work is to further explore the extragalactic origin of CD-51 4628 by looking for neutron-capture elements and measuring their abundances with so far unanalyzed blue spectra. Making use of iSpec, we have performed an LTE abundance analysis with the equivalent width method and the synthetic spectral fitting technique over the full wavelength range of 329 - 665 nm. We have redetermined the abundances reported in Nissen and Schuster (2010 & 2011) and extended to new neutron-capture elements. Comparing the abundance ratios [La/Ba], [Eu/Ba], [Mg/Fe], [Eu/Mg] and [Ba/Eu] of CD-51 4628 to literature values of Galactic in-situ stars and stars from satellite dwarf galaxies, we suggest that CD-51 4628 may have been accreted from Gaia-Enceladus or from a dwarf galaxy with a mass akin to Sculptor or Fornax.
| Item Type: | Thesis (Bachelor's Thesis) |
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| Supervisor name: | Tolstoy, E. |
| Degree programme: | Astronomy |
| Thesis type: | Bachelor's Thesis |
| Language: | English |
| Date Deposited: | 19 Jul 2022 10:19 |
| Last Modified: | 19 Jul 2022 10:19 |
| URI: | https://fse.studenttheses.ub.rug.nl/id/eprint/28025 |
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