Sökning: "stellar"
Visar resultat 1 - 5 av 162 avhandlingar innehållade ordet stellar.
1. Stellar Winds of Cool Giants : Investigating the Mass-Loss Mechanism of AGB Stars
Sammanfattning : Asymptotic giant branch (AGB) stars are luminous cool giants of low to intermediate mass that are strongly pulsating and non-spherical, with heavy mass loss through a stellar wind. The mass loss makes these stars important for galactic chemistry, as the wind enriches the interstellar medium with new elements and dust, and it determines the final fate of these stars. LÄS MER
2. Stellar kinematics in surveys and simulations
Sammanfattning : We study stellar motions in the Milky Way with N-body simulations and large astrometric samples from ESA's Gaia mission. We identify two kinematic populations for white dwarfs in the Solar neighbourhood. We also investigate the accreted halo and reveal two new structures. LÄS MER
3. Characterising Young Stellar Binaries
Sammanfattning : Stars are dispersed all over the sky within our Galaxy, appearing in large varieties of ages and sizes. How- ever, estimating said traits proves not to always be trivial, but certain circumstances allow us to probe the characteristics of stellar binaries. LÄS MER
4. On the Abundances of Li, Be and O in Metal-Poor Stars in the Galaxy
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
5. Atomic Processes in Stellar Atmospheres : Inelastic Collisions and Effects on Late-type Spectra
Sammanfattning : Chemical abundances as measured from stellar spectral lines are often subject to uncertainties due to lack of accurate data for inelastic collisions, which is needed for non-local thermodynamic equilibrium (non-LTE) modelling. For cool stars, understanding of collision processes with electrons and hydrogen atoms is required to achieve high precision measurements. LÄS MER