Dissertation Defense
Matheus de Jesus Castro
Program: Astronomia
Title: "Software development for heavy element abundance analysis of very metal-poor stars from lines in the ultravioleta"
Advisor: Profa. Dra. Beatriz Leonor S. Barbuy - IAG/USP
Judging Committee:
- Profa. Dra. Beatriz Leonor Silveira Barbuy (Orientadora) – IAG/USP
- Prof. Dr. Alan Alves Brito - IF/UFRGS
- Profa. Dra. Paula Rodrigues Teixeira Coelho - AG/USP
- Dr. Bruno Vaz de Castilho Souza - LNA/MCTI
Abstract
The First Stars program in the early 2000s collected high-resolution spectra of very metal-poor stars over 37 nights in the VLT. The data were analyzed and published in a series of 16 articles. The now ongoing project to build the CUBES spectrograph, to be installed at the VLT, will allow reaching stars with 𝑉 ≈ 18.0 in the near-UV, enlarging considerably the number of reachable metal-poor stars. For this reason, it was realized that a finer work on available lines in the near-UV of the stars observed in the First Stars project should be further developed. In this dissertation, the work on the halo metal-poor star CS 31082-001, which was revealed to be r-process-rich, has been revised. A series of spectral lines of heavy elements is studied, with a good number of them not studied before. The motivation for this extended work is the use of CUBES Spectrograph in the future. The results obtained from the CS 31082-001 were published in the paper “Reanalysis of neutron-capture elements in the benchmark r-rich star CS 31082-001” in MNRAS (Ernandes et al., 2023). The Multiple Element Abundance Fitting Software (MEAFS) was developed to help with measuring equivalent widths and abundances with a minimum interaction and high precision 𝜒² results. The software uses a combination of the method and the Nelder-Mead minimization to find chemical abundances of elements and create plots for analysis.
Keywords: software development, astronomical instrumentation, spectral synthesis, chemical abundances, stellar atmospheres