Sökning: "Galactic evolution"

Visar resultat 1 - 5 av 48 avhandlingar innehållade orden Galactic evolution.

1. 1. Stochastic Chemical Evolution : A Study of Scatter in Relative Elemental Abundances in Extremely Metal-poor Stars

   Författare :Torgny Karlsson; Bengt Gustafsson; Mike Edmunds; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; nucleosynthesis; chemical evolution; Galactic evolution; supernovae; chemical abundances; Population II stars; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

   Sammanfattning : Chemical evolution addresses the problem of the formation of the chemical elements and their evolution throughout the history of the universe. This thesis discusses in particular the chemical evolution in the young universe and what we may learn from the observations of the oldest stars. LÄS MER

3. 2. Dwarf and Subgiant Stars as Probes of Galactic Chemical and Dynamical Evolution

   Författare :Patrik Thorén; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Abundances; atomic data; Galactic evolution; late-type stars; main sequence stars; subgiants; Pop II; Pop I; stellar evolution; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

   Sammanfattning : Stellar chemical abundances provide astronomers with vital information about the production of chemical elements. Some stars preserve the composition of the environment in which they were born on their surfaces. LÄS MER

4. 3. Galactic Structure Revealed by Space Astrometry

   Författare :Johan Holmberg; Astronomi - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomi; cosmic chemistry; Galactic structure; Milky Way Galaxy; Galactic kinematics and dynamics; Galactic chemical evolution; moving groups; solar neighbourhood; dark matter; astrometry; Hipparcos; space research; Astronomy; rymdvetenskap; kosmisk kemi; Space technology; Rymdteknik; Fysicumarkivet A:2001:Holmberg;

   Sammanfattning : This work demonstrates how the structure of our Galaxy, the Milky Way, can be unveiled with the use of space astrometry. It consists of two parts, of which the first is a brief introduction to the fields of Galactic structure, covering the Galaxy's stellar constituents, how the Galaxy was formed and how it has evolved over time, both chemically and kinematically. LÄS MER

5. 4. The Milky Way as seen through Neutron-Capture Elements

   Författare :Rebecca Forsberg; Astrofysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemical abundances; Galactic archaeology; chemically peculiar star; heavy elements; Galactic disk; Galactic bulge; Galactic chemical evolution;

   Sammanfattning : 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. LÄS MER

7. 5. Clues to galaxy evolution from spectroscopic observations of Galactic centre stars

   Författare :Brian Thorsbro; Astronomi - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemical abundances; Late-type stars; Star clusters; Galactic center; Galaxy chemical evolution; Chemical enrichment;

   Sammanfattning : In this work we present results from spectroscopic observations of Galactic centre stars. High resolution stellar spectroscopy can be used to determine accurate stellar metallicities and abundances. Observing stars in the Galactic centre is challenging due to extreme extinction. LÄS MER