Sökning: "chemical abundances"

Visar resultat 16 - 20 av 51 avhandlingar innehållade orden chemical abundances.

  1. 16. On the Abundances of Li, Be and O in Metal-Poor Stars in the Galaxy

    Författare :Ana Elia García Pérez; Martin Asplund; Bengt Gustafsson; Francesca Primas; Beatriz Barbuy; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; galactic evolution; stellar abundances; stellar atmospheres; spectral line formation; stellar mixing; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Sammanfattning : Stellar atmospheres constitute excellent environments to study the chemical evolution of our Galaxy. The chemical composition of these atmospheres reflects the composition of the gas from where these stars were born. LÄS MER

  2. 17. Reactions on nanostructured and microporous surfaces

    Författare :Anna Clemens; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cu-CHA; XRD; solid-state ion-exchange; materials characterisation; electron microscopy; NH3-SCR; zeolites; catalysis; nanostructured graphite; Water ice; DRIFTS; XPS; NOx reduction; Cu-SSZ-13; temperature programmed desorption; ultra-high vacuum; intercalation; UV-Vis spectroscopy;

    Sammanfattning : Interactions between surfaces and molecules play a central role in various fields where catalysis is one example. In order to understand different surface processes, physicochemical characterisation of the surface materials and molecules is required. LÄS MER

  3. 18. The origin and chemical evolution of iron-peak and neutron-capture elements in the Milky Way disk

    Författare :Chiara Battistini; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: abundances; Stars: solar-type; Galaxy: disk; Galaxy: evolution; Galaxy: solar neighbourhood;

    Sammanfattning : All the elements heavier than Li are created during stellar evolution. Even if our knowledge of this process is good, many questions still remain. LÄS MER

  4. 19. Exploring the Chemical Evolution of Globular Clusters and their Stars : Observational Constraints on Atomic Diffusion and Cluster Pollution in NGC 6752 and M4

    Författare :Pieter Gruyters; Andreas Korn; Piercarlo Bonifacio; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: abundances – stars: atmospheres – stars: fundamental parameters – globular clusters: individual: NGC 6752 and M4 – techniques: spectroscopic; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

    Sammanfattning : Through the cosmic matter cycle, the chemical evolution of the Milky Way is imprinted in the elemental abundance patterns of late-type stars (spectral types F to K). Due to their long lifetimes ( 1 Hubble time), these stars are of particular importance when it comes to studying the build-up of elements during the early times of our Galaxy. LÄS MER

  5. 20. Galactic archaeology with metal-poor stars

    Författare :Thomas Nordlander; Andreas J. Korn; Karin Lind; Ulrike Heiter; David L. Lambert; Uppsala universitet; []
    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