Search for dissertations about: "Astrofysik"

Showing result 1 - 5 of 470 swedish dissertations containing the word Astrofysik.

  2. 1. Searching for Dyson spheres in the Milky Way

    Author : Matías Suazo; Erik Zackrisson; Andreas J. Korn; Hector Socas-Navarro; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Extraterrestrial intelligence; infrared:stars; Astronomi och astrofysik; Astronomy and Astrophysics;

    Abstract : The quest to find intelligent extraterrestrial life has captivated humanity for a long time, motivating the development of various strategies to search for signs of advanced civilizations. These strategies comprise multiple techniques and span different regions of the electromagnetic spectrum. READ MORE

  4. 2. Mass Loss of Evolved Stars : Improving Mass-Loss Rates and Distances

    Author : Miora Andriantsaralaza; Paul Barklem; Elvire De Beck; Susanne Höfner; Jacco van Loon; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; AGB stars; Mass loss; Distance; Circumstellar matter; Radio interferometry; Stellar evolution; Fysik med inriktning mot astrofysik; Physics with specialization in Astrophysics;

    Abstract : 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. READ MORE

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

    Author : Pieter Gruyters; Andreas Korn; Piercarlo Bonifacio; Uppsala universitet; []
    Keywords : 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;

    Abstract : 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. READ MORE

  6. 4. Magnetic Fields and Chemical Spots in HgMn Stars

    Author : Vitalii Makaganiuk; Oleg Kochukhov; Nikolai Piskunov; Gregg Wade; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Chemically peculiar stars; magnetic fields; spectropolarimetry; Doppler imaging; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

    Abstract : Mercury-manganese (HgMn) stars belong to the class of chemically peculiar (CP) stars. It was recently discovered that some HgMn stars have spots of chemical elements on their surfaces. READ MORE

  7. 5. Atomic Processes in Stellar Atmospheres : Inelastic Collisions and Effects on Late-type Spectra

    Author : Yeisson Fabian Martinez Osorio; Paul Barklem; Karin Lind; Nikolai Piskunov; Carlos Allende Prieto; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Spectral line: formation; atomic data; stellar abundances.; Fysik med inriktning mot astrofysik; Physics with specialization in Astrophysics;

    Abstract : 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. READ MORE