Rebecca Forsberg
Doctoral student
The Milky Way as seen through Neutron-Capture Elements
Author
Summary, in English
Through stars, the formation and evolution of the Galaxy goes hand-in-hand with the cosmic origin of the elements. As stars form, they carry chemical fingerprints of their birthclouds, providing us with chemical timestamps of the Galaxy.
The detailed history of the Galactic disk and bulge is still to be untagled. The same goes for the origin of elements – where some still have elusive origins. Disentagling the origin of the Galaxy and the elements can only be acchived by continued efforts by combining the most accurate and precise data with the latest state-of-the art theoretical models.
In this thesis, I present high-precision chemical abundances of red giant stars in the Galactic disk and bulge, obtained by careful analysis of high-resolution optical and infrared spectra. Using red giant stars in the bulge and disk populations allows for an unique differential comparison of the two Galactic components. I focus the analysis to obtain abundances of neutron-capture elements, which can shed new light on the origin of the Galactic components.
The abundance trends of the Galactic bulge show great similarities with the Galactic (thick) disk, pointing at a similar history. However, there are possible enrichments in both lanthanum and molybdenum, which require further follow-up studies to confirm. I identify a chemically-peculiar star in the bulge, standing out by its high abundances of europium and molybenum.
Finally, I demonstrate the need for high-resolution and spectra in order to access abundances of neutron-capture elements in the infrared. Including heavy elements is essential in getting the full chemical view of the Galaxy, which is shown in this thesis.
The detailed history of the Galactic disk and bulge is still to be untagled. The same goes for the origin of elements – where some still have elusive origins. Disentagling the origin of the Galaxy and the elements can only be acchived by continued efforts by combining the most accurate and precise data with the latest state-of-the art theoretical models.
In this thesis, I present high-precision chemical abundances of red giant stars in the Galactic disk and bulge, obtained by careful analysis of high-resolution optical and infrared spectra. Using red giant stars in the bulge and disk populations allows for an unique differential comparison of the two Galactic components. I focus the analysis to obtain abundances of neutron-capture elements, which can shed new light on the origin of the Galactic components.
The abundance trends of the Galactic bulge show great similarities with the Galactic (thick) disk, pointing at a similar history. However, there are possible enrichments in both lanthanum and molybdenum, which require further follow-up studies to confirm. I identify a chemically-peculiar star in the bulge, standing out by its high abundances of europium and molybenum.
Finally, I demonstrate the need for high-resolution and spectra in order to access abundances of neutron-capture elements in the infrared. Including heavy elements is essential in getting the full chemical view of the Galaxy, which is shown in this thesis.
Department/s
- Astrophysics
Publishing year
2023-10-10
Language
English
Full text
- Available as PDF - 21 MB
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Document type
Dissertation
Publisher
Lund University
Topic
- Astronomy, Astrophysics and Cosmology
Keywords
- Chemical abundances
- Galactic archaeology
- chemically peculiar star
- heavy elements
- Galactic disk
- Galactic bulge
- Galactic chemical evolution
Status
Published
Supervisor
- Nils Ryde
- Anders Johansen
- Henrik Jönsson
ISBN/ISSN/Other
- ISBN: 978-91-8039-714-8
- ISBN: 978-91-8039-715-5
Defence date
3 November 2023
Defence time
09:00
Defence place
Lundmarksalen, Sölvegatan 27, Lund.
Opponent
- Alejandra Recio-Blanco (Astronomer (1st class))