Search for dissertations about: "dwarf"

Showing result 21 - 25 of 74 swedish dissertations containing the word dwarf.

  2. 21. A Photometric Study of the Galactic Disks based on Strömgren Photometry

    Author : Anna Arnadottir; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; density parameters; formation.; metallicity distribution function; thin disk; metallicities. Galaxy - thick disk; colours; Photometry - Strömgren; luminosities; SDSS. Stars - classification;

    Abstract : One of the key questions in todays galaxy research is the formation and evolution of disk galaxies such as the Milky Way. Using observations in the intermediate band Stromgren uvby filter system we have investigated how both density and metallicity varies within the Galactic disks in order to learn more about the Galaxy and its past. READ MORE

  4. 22. Interacting Giants and Compact Stars

    Author : Alexey Bobrick; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; stars Binaries: General; stars : neutron; stars : subdwarfs; stars : supergiants; hydrodynamics; nuclear reactions; nucleosynthesis; abundances; stars Binaries: General; stars : neutron; stars : subdwarfs; stars : supergiants; hydrodynamics; nuclear reactions; nucleosynthesis; abundances; Fysicumarkivet A:2021:Bobrick;

    Abstract : This thesis is based on four papers dealing with various aspects of interactions in binary stars. Interactions between stars occur at nearly all stages of their evolution and can take many forms. READ MORE

  5. 23. Inside Pulsating White Dwarfs: Clues from time-resolved spectroscopy

    Author : Rubina Kotak; Astronomi - Genomgår omorganisation; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; pulsating white dwarfs; convection; asteroseismology; Astronomi; Astronomy; spectroscopy; Fysicumarkivet A:2002:Kotak;

    Abstract : Several analyses using time-resolved optical spectrocopy of pulsating white dwarfs are presented. The data have been put to a number of uses. First, line-of-sight velocities associated with the pulsations have been measured in three hydrogen-atmosphere white dwarfs (DAVs), bringing the total number of such measurements up to five. READ MORE

  6. 24. Magnetic fields of cool stars from near-infrared spectropolarimetry

    Author : Alexis Lavail; Oleg Kochukhov; Nikolai Piskunov; Gaitee Hussain; Jeff Valenti; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; stars: magnetic field; stars: pre-main-sequence; stars: late-type; techniques: spectroscopic; techniques: polarimetric; Astronomy; Astronomi;

    Abstract : Magnetic fields rule many physical processes in and around stars throughout their lifetime. All cool stars possess a magnetic field, likely generated by dynamo processes. In order to properly understand the evolution of cool stars, we need to understand their magnetism. READ MORE

  7. 25. Late Weichselian and early Holocene changes of vegetation, climate and sea level on the Skagi peninsula, northern Iceland

    Author : Mats Rundgren; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; asthenosphere viscosity; glacial loading unloading; marine polar front migrations; sea-level change; climate change; vegetation change; Early Holocene; Late Weichselian; Iceland; Lake sediments; Skagi peninsula; Geology; physical geography; Geologi; fysisk geografi;

    Abstract : Sediment sequences from five lakes on the Skagi peninsula, northern Iceland, were subjected to mineral magnetic analysis, carbon analysis, pollen analysis, plant macrofossil analysis, diatom analysis, radiocarbon dating and tephra analysis in order to make detailed reconstructions of vegetation, climate and sea level during the Late Weichselian and Early Holocene. The main purpose was to investigate if the dramatic deglacial climatic shifts recorded in proxy records from the North Atlantic region, such as ice cores, marine sediments and lake sediments, also are registered in Skagi lake sediments, which would be expected considering Iceland´s position in the middle of the North Atlantic Ocean, within the range of the Late Weichselian–Early Holocene migrations of the marine polar front. READ MORE