Sökning: "astronomi"

Visar resultat 1 - 5 av 462 avhandlingar innehållade ordet astronomi.

  1. 1. Numerical simulations of type III planetary migration

    Författare :Adam Peplinski; Pawel Artymowicz; Garrelt Mellema; John Papaloizou; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; planetary system formation; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; astronomi; accretion; accretion discs; hydrodynamics; methods: numerical; planets and satellites: formation; Astronomy; Astronomi;

    Sammanfattning : Planets are believed to form in primordial gas-dust discs surrounding newborn stars. An important breakthrough in our understanding of planetary formation was the discovery of extra-solar planets around sun-like stars, especially the frequent occurrence of giant planets on close orbits (hot Jupiters). LÄS MER

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

    Författare :Johan Warell; Nick Thomas; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; 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. 3. Measuring the solar atmosphere

    Författare :Jaime de la Cruz Rodríguez; Göran Scharmer; Dan Kiselman; Mats Carlsson; Gianna Cauzzi; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; 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. 4. Studies of Gas Disks in Binary Systems

    Författare :Miguel de Val Borro; Pawel Artymowicz; William Benz; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; 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. 5. The faintest stars : A study of white, red and brown dwarfs

    Författare :Leif Festin; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Astronomy; brown dwarfs; white dwarfs; M dwarf; low luminosity; luminosity function; mass function; Pleiades; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : The local space density of the faintest stars, including M dwarfs, white dwarfs and brown dwarfs has been studied by two different methods.By using dark nebulae as opaque outer screens, the luminosity functions of M dwarfs and white dwarfs were studied as volume-limited and dynamically unbiassed foreground samples. LÄS MER