Sökning: "main sequence stars"

Visar resultat 6 - 10 av 17 avhandlingar innehållade orden main sequence stars.

1. 6. Searches for Particle Dark Matter : Dark stars, dark galaxies, dark halos and global supersymmetric fits

   Författare :Pat Scott; Joakim Edsjö; Lars Bergström; Jan Conrad; Dan Hooper; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; dark matter; supersymmetry; gamma rays; dwarf galaxies; stellar evolution; cosmological perturbations; phase transitions; statistical techniques; Astroparticle physics; Astropartikelfysik; Astroparticle physics; Astropartikelfysik; Cosmology; Kosmologi; Elementary particle physics; Elementarpartikelfysik; Computational physics; Beräkningsfysik; Formation and development of stars; Stjärnors bildning och utveckling; High energy astrophysics; Högenergiastrofysik; teoretisk fysik; Theoretical Physics;

   Sammanfattning : The identity of dark matter is one of the key outstanding problems in both particle and astrophysics. In this thesis, I describe a number of complementary searches for particle dark matter. LÄS MER

3. 7. 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

4. 8. Metallicity determination of M dwarfs

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

   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

5. 9. Extrasolar Kuiper and asteroid belts Modelling far-infrared dust emission

   Författare :Joachim Wiegert; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: binaries - Stars: circumstellar matter - Infrared: stars - Infrared: planetary systems - Submillimeter: stars;

   Sammanfattning : The first detections of circumstellar dust emission were announced in the mid 1980s. Direct observations of the edge-on disc of beta Pictoris provided evidence that the dust was part of possible planetary systems. About a decade later, in 1995, the first confirmed extrasolar planet around a main sequence star (51 Pegasi b) was announced. LÄS MER

7. 10. 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