Search for dissertations about: "Institutionen för astronomi"

Showing result 1 - 5 of 332 swedish dissertations containing the words Institutionen för astronomi.

  1. 1. Measuring the solar atmosphere

    Author : Jaime de la Cruz Rodríguez; Göran Scharmer; Dan Kiselman; Mats Carlsson; Gianna Cauzzi; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Sun; Chromosphere; Spectropolarimetry; Solar observations; Spectral lines; Solar magnetic fields; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : The new CRISP filter at the Swedish 1-m Solar Telescope provides opportunities for observing the solar atmosphere with unprecedented spatial resolution and cadence. In order to benefit from the high quality of observational data from this instrument, we have developed methods for calibrating and restoring polarized Stokes images, obtained at optical and near infrared wavelengths, taking into account field-of-view variations of the filter properties. READ MORE

  2. 2. Studies of Gas Disks in Binary Systems

    Author : Miguel de Val Borro; Pawel Artymowicz; William Benz; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : There are over 300 exoplanets detected through radial velocity surveys and photometric studies showing a tremendous variety of masses, compositions and orbital parameters. Understanding the way these planets formed and evolved within the circumstellar disks they were initially embedded in is a crucial issue. READ MORE

  3. 3. Young stars and outflows : case studies of three different regions

    Author : Magnus Gålfalk; Göran Olofsson; Klaus Werner Hodapp; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Star formation; Young stars; Outflows; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : Mass is clearly the most important parameter of a star as it determines the phases it will go through, its physical parameters, the elements produced and its life span. Two important processes that occur simultaneously in young stars are directly related to the final mass a star ends up with; the accretion of material onto the star from a circumstellar disk and the bipolar outflow of material from the star. READ MORE

  4. 4. Dynamics of the interstellar matter in galaxies : isolated barred spiral galaxies : cloud formation processes

    Author : Kristen Helmuth; John Beckman; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : The dynamical components of six isolated barred spiral (SB) galaxies are investigated. No evidence is found supporting the hypothesis of a low amount of dark matter being characteristic of SB galaxies. The presence of companion galaxies is found to correlate with an increased statistical spread in the neutral hydrogen (HI) extent. READ MORE

  5. 5. Asymptotic Giant Branch stars viewed up-close and far-off : The physics, chemistry, and evolution of their circumstellar envelopes

    Author : Matthias Maercker; Hans Olofsson; Fredrik L. Schöier; Laurentius B. F. M. Waters; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; AGB stars; evolution; mass-loss; abundances; Astronomy; Astronomi; Astronomy; astronomi;

    Abstract : The asymptotic giant branch (AGB) is the last stage of stellar evolution for stars with masses between 0.8-8 M(sun). This phase is characterised by an intense mass loss, which builds up a circumstellar envelope of dust and gas(CSE). It is through this process that the AGB stars contribute to the chemical evolution of galaxies. READ MORE