Sökning: "stellar evolution"
Visar resultat 11 - 15 av 76 avhandlingar innehållade orden stellar evolution.
11. Star clusters as engines of galaxy evolution
Sammanfattning : Feedback in star forming galaxies is the key process that regulates how many stars form given the available gas reservoir. The radiation, energy and momentum released by the stellar activity and the active galactic nuclei change the physical properties of the gas in the galaxy such as the ionisation state, the density and the kinematics. LÄS MER
12. The cosmic origin of fluorine and sulphur: Infrared spectroscopic studies of red giants
Sammanfattning : Disregarding the small primordial traces of the lightest elements, all metals have been formed in stellar processes, which means that the relative amount of metals in the Universe increases for every stellar generation. This build-up of elements is called chemical evolution and might be used both to constrain stellar models as well as understanding the formation and evolution of stellar populations. LÄS MER
13. Radial Velocities Without Spectroscopy -Astrometric determination of stellar radial motion
Sammanfattning : This work demonstrates the determination of absolute stellar radial velocities from geometrical principles, i.e. using astrometry. Such `astrometric radial velocities' are obtained independently of spectroscopic information. LÄS MER
14. The galactic scale impact of feedback from individual stars
Sammanfattning : Feedback from stars is essential for the formation and evolution of galaxies. It is an energy source that drives gas motions and chemically enriches the galaxy by supplying metals. Without this stellar feedback, numerical galaxy simulations result in galaxies with little resemblance to those observed in our Universe. LÄS MER
15. Mass Loss of Evolved Stars : Improving Mass-Loss Rates and Distances
Sammanfattning : In the final stages of their lives, low to intermediate-mass stars enter the Asymptotic Giant Branch (AGB) phase, where they experience significant mass loss through dusty stellar winds. This mass loss is pivotal, not only for the chemical enrichment of the interstellar medium, setting the stage for new stars and planets to form, but also in dictating the evolution and the ultimate fate of the stars themselves. LÄS MER