Sökning: "Galactic Bulge"

Visar resultat 1 - 5 av 10 uppsatser innehållade orden Galactic Bulge.

1. 1. Measuring copper abundances in the Galactic Bulge

   Kandidat-uppsats, Lunds universitet/Astrofysik; Lunds universitet/Fysiska institutionen

   Författare :Nikolei Höglinger; [2024]
   Nyckelord :Copper; Galaxy: abundances; Galaxy: bulge; Chemical Evolution; Physics and Astronomy;

   Sammanfattning : Context: The chemical evolution of Cu in the Galactic bulge have been studied in a few studies using red giant branch stars, but the ages of individual red giant stars are difficult to determine. In addition, the bulge has been a challenging region of the Milky Way galaxy to obtain high-resolution spectra of stars, except when observing through certain few small fields into the bulge that are known to have low extinction. LÄS MER

3. 2. The quest for a classical bulge - a study of kinematics, abundances, and ages using microlensed dwarf stars and Gaia

   Master-uppsats, Lunds universitet/Astrofysik; Lunds universitet/Fysiska institutionen

   Författare :Calum Kvernes Macpherson; [2023]
   Nyckelord :Bulge; Milky Way; Kinematics; Galpy; Dwarf Stars; Physics and Astronomy;

   Sammanfattning : Context: We present an kinematical analysis of 90 F and G type dwarf, turn-off, and subgiant stars in the Galactic bulge. These stars were observed with high-resolution spectrographs during gravitational microlensing events This allowed for their ages, abundances, and radial velocities to be ascertained while they were significantly brighter. LÄS MER

4. 3. Potassium in the Galactic Bulge - as traced by microlensed dwarf & sub-giant stars

   Kandidat-uppsats, Lunds universitet/Astrofysik; Lunds universitet/Fysiska institutionen

   Författare :Lukas Jönsson; [2023]
   Nyckelord :Nucleosynthesis; Galactic Bulge; Potassium; Non-Local-Thermal-Equilibrium; Physics and Astronomy;

   Sammanfattning : During this report the potassium (K) trend in the Galactic Bulge, with respect to metallicity and various α-elements, has been computed and evaluated by a method of line synthesis on the 7698.96 ̊A KI line (7699 KI), where Non-Local-Thermal-Equilibrium (NLTE) effects have been considered. LÄS MER

5. 4. Machine Learning for Stellar Spectra : Anomaly Detection in stellar spectra using Unsupervised Random ForestSpectral Analysis using Variational Autoencoders

   Master-uppsats, Luleå tekniska universitet/Rymdteknik

   Författare :Mihir Paranjape; [2021]
   Nyckelord :Stellar spectra; outlier; VAE; neural network; machine learning; Gaia-ESO;

   Sammanfattning : This thesis was carried out in two parts. The stellar spectral data was used from the Gaia-ESO survey. The data used was fromthe public archive as well as data received from Dr. Recio-Blanco at Observatoire Cote D'Azure. LÄS MER

7. 5. From the bulge region to the outer disk: Tracing the α-enhancement level in the Galactic thin and thick disks

   Kandidat-uppsats, Lunds universitet/Astronomi - Genomgår omorganisation

   Författare :Elin Sandvik; [2020]
   Nyckelord :Chemical abundance; star formation rate; initial-mass function; APOGEE; Milky Way; Physics and Astronomy;

   Sammanfattning : One of the biggest mysteries astronomers wish to unveil is the formation and evolution of galaxies. Properties of our own galaxy, the Milky Way, can provide great insight into these. The star formation rate (SFR) and whether it varies with distance from the galactic centre (GC), is one of these properties. LÄS MER