Sökning: "Astronomi Astronomy"

Visar resultat 1 - 5 av 485 avhandlingar innehållade orden Astronomi Astronomy.

1. 1. Gas Production in Distant Comets

   Författare :Marcus Gunnarsson; F Peter Schloerb; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Comets; Radio Astronomy; Molecular Spectroscopy; Coma Models; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

   Sammanfattning : Molecular spectroscopy at radio wavelengths is a tool well suited for studying the composition and outgassing kinematics of cometary comae. This is particularly true for distant comets, i.e. comets at heliocentric distances greater than a few AU, where the excitation of molecules is inefficient other than for rotational energy levels. LÄS MER

3. 2. 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

4. 3. Chemical Abundance Analysis of Population II Stars : The Summary Includes a Background in General Astronomy

   Författare :Karin Jonsell; Bengt Gustafsson; Bengt Edvardsson; Paul Barklem; Christopher Sneden; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomy; Galactic evolution; Halo; Milky Way; Oxygen; r-element; s-element; Stellar abundances; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

   Sammanfattning : We are made of stardust in the sense that most atomic nuclei around us have been formed by stars. Stars synthesise new elements and expel them to the interstellar medium, from which later new generations of stars are born. We can map this chemical evolution by analysing the atmospheric contents of old Galactic halo stars. LÄS MER

5. 4. 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

7. 5. 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