Sökning: "stellar evolution"

Visar resultat 1 - 5 av 72 uppsatser innehållade orden stellar evolution.

1. 1. The visibility of stellar transients in the Galactic Centre

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

   Författare :Jonathan Ström; [2024]
   Nyckelord :Physics and Astronomy;

   Sammanfattning : A semi-analytical simulation was developed to evaluate the K-band magnitudes of Red Giants [0.96 - 1.02 M⊙] orbiting the supermassive black hole in the galactic centre. The model assumed star formation between 10-12 Gyrs ago and by following the IMF and applying a random age condition, a stellar population was created. LÄS MER

3. 2. 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

4. 3. 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

5. 4. Starshades: Geoengineering Solutions and Technosignatures in Direct Imaging Phase Curves

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

   Författare :Claudia Skoglund; [2023]
   Nyckelord :Starshades; extraterrestrial intelligence; stellar evolution; technosignatures; phase curves; direct imaging; habitable zone.; Physics and Astronomy;

   Sammanfattning : The stellar luminosity increases as a star evolves which inevitably yields a higher temperature on planets in orbit around the star. It is reasonable to assume that intelligent civilizations would tackle this issue through installing artificial structures that can alter the radiation received by the planet. LÄS MER

7. 5. What limits the luminosity of red supergiants?

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

   Författare :Eric Svensson; [2023]
   Nyckelord :Stellar evolution; Red supergiants; Red giants; Luminosity; Binary stars; Binary star systems; Binary star interactions; Binary stellar evolution; Humphreys-Davidson limit; Upper luminosity limit; BSE; Population synthesis; Simulations; M31; LMC; SMC; Metallicity; Mass transfer; Merging; Physics and Astronomy;

   Sammanfattning : The observed upper limit of the luminosity of red supergiants, often called the Humphreys-Davidson limit, has recently been shown to be independent of metallicity and to not be explainable by single star evolution – findings that both contradict established ideas of the origins of the limit. It is now known that the vast majority of stars with sufficient mass to possibly evolve into red supergiants above the limit interact with companion stars at some point during their lives. LÄS MER