Sökning: "Galaxy: evolution"

Visar resultat 11 - 15 av 74 avhandlingar innehållade orden Galaxy: evolution.

1. 11. Determination of stellar ages and star formation histories - a Bayesian approach With an application to nearby F and G stars

   Författare :Bjarne Rosenkilde Jørgensen; Astronomi - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomi; Astronomy; Galaxy evolution; Statistical methods; Stellar evolution; Data analysis;

   Sammanfattning : In order to understand the formation and evolution of the Galaxy it is imperative to know when different components formed. This means at the most basic level that we need to know the ages of stars. The present work demonstrates the many problems inherent in determining the ages of stars through comparison with stellar evolutionary models. LÄS MER

3. 12. The spatial distribution of Lyman alpha from star-forming galaxies in the low redshift Universe

   Författare :Armin Rasekh; Göran Östlin; Roland Bacon; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lyman alpha; star-forming galaxies; Galaxy evolution; Epoch of Reionisation; galaxy morphology; Lyman continuum diagnostics; gas kinematics of galaxies; Astronomy; astronomi;

   Sammanfattning : The Lyman alpha (Lyα) emission line from the recombination of hydrogen atoms is predicted to be the strongest spectral feature of galaxies. This emission line is regularly used to detect and characterise high redshift galaxies. However, studying this spectral line is challenging. LÄS MER

4. 13. Star clusters as engines of galaxy evolution

   Författare :Mattia Sirressi; Angela Adamo; Matthew J. Hayes; Johan Fynbo; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Stars form and live in hierarchical structures such as star clusters on the smallest scales up to groups of galaxies on the largest scales. The role of young and massive star clusters in the evolution of the host galaxies is one of the most active fields of research in modern astronomy. LÄS MER

5. 14. Star clusters as engines of galaxy evolution

   Författare :Mattia Sirressi; Angela Adamo; Matthew Hayes; Paul Crowther; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Extragalactic astronomy; Galaxies; Star formation; Interstellar medium; Stellar feedback; Ultraviolet surveys; Hubble Space Telescope; Spectroscopy; Data analysis; Astronomy; astronomi;

   Sammanfattning : Feedback in star forming galaxies is the key process that regulates how many stars form given the available gas reservoir. The radiation, energy and momentum released by the stellar activity and the active galactic nuclei change the physical properties of the gas in the galaxy such as the ionisation state, the density and the kinematics. LÄS MER

7. 15. 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