Sökning: "metallicity"

Visar resultat 1 - 5 av 23 avhandlingar innehållade ordet metallicity.

  1. 1. Metallicity determination of M dwarfs

    Författare :Sara Lindgren; Ulrike Heiter; Ansgar Reiners; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; stars: low mass - stars: abundances; fundamental parameters - technique: spectroscopic; photometric - planets and satellites: formation; stars:low-mass–stars:abundances–techniques:spectroscopic; Astronomy; Astronomi;

    Sammanfattning : M dwarfs constitute around 70% of all stars in the local Galaxy. Their multitude together with their long main-sequence lifetimes make them important for studies of global properties of the Galaxy such as the initial mass function or the structure and kinematics of stellar populations. LÄS MER

  2. 2. Free Metal Clusters Studied by Photoelectron Spectroscopy

    Författare :Tomas Andersson; Olle Björneholm; Maxim Tchaplyguine; Paolo Piseri; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; clusters; nanoparticles; electronic structure; photoelectron spectroscopy; synchrotron radiation; surface segregation; nanoalloys; size-dependence; metallicity; plasmons; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : Clusters are aggregates of a finite number of atoms or molecules. In the present work, free clusters out of metallic parent materials have been created and studied by synchrotron radiation-based photoelectron spectroscopy. The clusters have been formed and studied in a beam and the electronic structure of the clusters has been investigated. LÄS MER

  3. 3. Observations of rare supernovae and their environments

    Författare :Francesco Taddia; Jesper Sollerman; Maryam Modjaz; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Supernova; stellar evolution; metallicity; circumstellar interaction; Astronomy; astronomi;

    Sammanfattning : Supernovae (SNe) are the final stage in the life of massive stars. Their explosion unbinds the progenitor star revealing its inner layers. The SN ejecta interact with the circumstellar material (CSM), providing further information on the progenitor star. LÄS MER

  4. 4. A Photometric Study of the Galactic Disks based on Strömgren Photometry

    Författare :Anna Arnadottir; Astronomi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; density parameters; formation.; metallicity distribution function; thin disk; metallicities. Galaxy - thick disk; colours; Photometry - Strömgren; luminosities; SDSS. Stars - classification;

    Sammanfattning : One of the key questions in todays galaxy research is the formation and evolution of disk galaxies such as the Milky Way. Using observations in the intermediate band Stromgren uvby filter system we have investigated how both density and metallicity varies within the Galactic disks in order to learn more about the Galaxy and its past. LÄS MER

  5. 5. The nature of stars with a common origin: clues from metallicity, elemental abundances, and kinematics

    Författare :Cheng Liu; Astronomi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Stars: abundances; Galaxy: evolution; Galaxy: solar neighbourhood; Galaxy: bulge; Galaxy: globular clusters;

    Sammanfattning : Most of field stars originate from dissolved star clusters. If the gas cloud is well mixed the stars in the cluster are expected to be chemically homogenous. LÄS MER