Sökning: "Astronomi"

Visar resultat 1 - 5 av 644 avhandlingar innehållade ordet Astronomi.

1. 1. Regolith Properties of Mercury Derived from Observations and Modelling

   Författare :Johan Warell; Nick Thomas; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Mercury; Moon; imaging; photometry; spectroscopy; regolith; space weathering; light scattering; spectral modelling; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

   Sammanfattning : The properties of Mercury's regolith have been investigated at optical and near-infrared wavelengths with high-resolution imaging, photometric, and spectroscopic observations with the Swedish Vacuum Solar Telescope and the Nordic Optical Telescope. A new global optical map at a spatial resolution of 200 km shows that the well known (from Mariner 10) and poorly known hemispheres are indistinguishable with respect to the distribution, number density, and morphological parameters of bright albedo features. LÄS MER

3. 2. Measuring the solar atmosphere

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

   Sammanfattning : 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. LÄS MER

4. 3. Studies of Gas Disks in Binary Systems

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

   Sammanfattning : 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. LÄS MER

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

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

   Sammanfattning : 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. LÄS MER

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

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

   Sammanfattning : 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. LÄS MER