Search for dissertations about: "stellar abundances"

Showing result 6 - 10 of 34 swedish dissertations containing the words stellar abundances.

  2. 6. Molecules and Dust around AGB stars : Mass-loss rates and molecular abundances

    Author : Sofia Ramstedt; Hans Olofsson; Fredrik Schöier; José Cernicharo; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; AGB stars; mass-loss; circumstellar abundances; Formation and development of stars; Stjärnors bildning och utveckling; Astronomy; astronomi;

    Abstract : All stars with a stellar mass of about 0.8–8 MSun will end their lives as asymptotic giant branch (AGB) stars. Through their extensive mass loss the AGB stars constitutes an important source of nuclear processed material. READ MORE

  4. 7. The cosmic origin of fluorine and sulphur: Infrared spectroscopic studies of red giants

    Author : Henrik Jönsson; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Chemical evolution; near-infrared and mid-infrared spectroscopy; stellar abundances;

    Abstract : Disregarding the small primordial traces of the lightest elements, all metals have been formed in stellar processes, which means that the relative amount of metals in the Universe increases for every stellar generation. This build-up of elements is called chemical evolution and might be used both to constrain stellar models as well as understanding the formation and evolution of stellar populations. READ MORE

  5. 8. Asymptotic Giant Branch stars viewed up-close and far-off : The physics, chemistry, and evolution of their circumstellar envelopes

    Author : Matthias Maercker; Hans Olofsson; Fredrik L. Schöier; Laurentius B. F. M. Waters; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; AGB stars; evolution; mass-loss; abundances; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : The asymptotic giant branch (AGB) is the last stage of stellar evolution for stars with masses between 0.8-8 M(sun). This phase is characterised by an intense mass loss, which builds up a circumstellar envelope of dust and gas(CSE). It is through this process that the AGB stars contribute to the chemical evolution of galaxies. READ MORE

  6. 9. On the Winds of Carbon Stars and the Origin of Carbon : A Theoretical Study

    Author : Lars Mattsson; Susanne Höfner; Nils Bergvall; Kjell Olofsson; Martin Groenewegen; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; AGB stars; carbon stars; mass loss; stellar winds; circumstellar matter; cosmic dust; stellar evolution; nucleosynthesis; galactic chemical evolution; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; Astronomi; Fysik; Physics;

    Abstract : Carbon is the basis for life, as we know it, but its origin is still largely unclear. Carbon-rich Asymptotic Giant Branch (AGB) stars (carbon stars) play an important rôle in the cosmic matter cycle and may contribute most of the carbon in the Galaxy. READ MORE

  7. 10. Chemical Abundance Analysis of Population II Stars : The Summary Includes a Background in General Astronomy

    Author : Karin Jonsell; Bengt Gustafsson; Bengt Edvardsson; Paul Barklem; Christopher Sneden; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomy; Galactic evolution; Halo; Milky Way; Oxygen; r-element; s-element; Stellar abundances; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Abstract : We are made of stardust in the sense that most atomic nuclei around us have been formed by stars. Stars synthesise new elements and expel them to the interstellar medium, from which later new generations of stars are born. We can map this chemical evolution by analysing the atmospheric contents of old Galactic halo stars. READ MORE