Sökning: "stars: abundances"

Visar resultat 1 - 5 av 34 avhandlingar innehållade orden stars: abundances.

  1. 1. Solar Type Stars as Calibrators A Photometric and Spectroscopic Study on the Atmospheric Properties of Late-type Stars

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Anna Önehag; Uppsala universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: atmospheres; stars: late-type; techniques: photometric; stars: abundances; techniques: spectroscopic; Astronomy; Astronomi;

    Sammanfattning : Detailed knowledge of solar-type stars is essential in the understanding of the evolutionary past, presence and future of the Sun as well as the formation of its planetary system. Moreover, solar-type stars are of key significance for the study of the evolution of the Galaxy. The ages of solar-type stars map the full galactic evolution. LÄS MER

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

    Detta är en avhandling från Stockholm : Department of Astronomy, Stockholm University

    Författare :Sofia Ramstedt; Stockholms universitet.; [2009]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AGB stars; mass-loss; circumstellar abundances; NATURAL SCIENCES Physics Astronomy and astrophysics Formation and development of stars; NATURVETENSKAP Fysik Astronomi och astrofysik Stjärnors bildning och utveckling; Astronomy; astronomi;

    Sammanfattning : 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. LÄS MER

  3. 3. Galactic archaeology with metal-poor stars

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Thomas Nordlander; Uppsala universitet.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: abundances; radiative transfer; stars: Population II; stars: Population III;

    Sammanfattning : The chemical fingerprints of old, metal-poor stars can be used to unravel the events of the newborn Universe and help us understand the properties of the first stars and star clusters. The study of nearby stars to infer properties in the distant past is often referred to as Galactic archaeology. LÄS MER

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

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Patrik Thorén; Uppsala universitet.; [2001]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Abundances; atomic data; Galactic evolution; late-type stars; main sequence stars; subgiants; Pop II; Pop I; stellar evolution; Astronomi; NATURAL SCIENCES Physics Astronomy and astrophysics; NATURVETENSKAP Fysik 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

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

    Detta är en avhandling från Stockholm : Department of Astronomy, Stockhoom University

    Författare :Matthias Maercker; Stockholms universitet.; [2009]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AGB stars; evolution; mass-loss; abundances; NATURAL SCIENCES Physics Astronomy and astrophysics Astronomy; NATURVETENSKAP Fysik Astronomi och astrofysik Astronomi; astronomi; Astronomy;

    Sammanfattning : 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. LÄS MER