Sökning: "astronomy and astrophysics"

Visar resultat 1 - 5 av 470 avhandlingar innehållade orden astronomy and astrophysics.

1. 1. From irrotational flows to turbulent dynamos

   Författare :Fabio Del Sordo; Axel Brandenburg; Mordecai-Mark Mac Low; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; astrophysics; magnetic fields; insterstellar medium; MHD; dynamo; turbulence; instability; Astronomy; astronomi;

   Sammanfattning : Many of the celestial bodies we know are found to be magnetized:the Earth, many of the planets so far discovered, the Sun and other stars,the interstellar space, the Milky Way and other galaxies.The reason for that is still to be fully understood, and this work is meant to be a step in that direction. LÄS MER

3. 2. Thermophysical Modelling and Mechanical Stability of Cometary Nuclei

   Författare :Björn Davidsson; Dina Prialnik; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Comets; Tidal physics; Light scattering; Radiative transfer; Thermophysics; Gas kinetics; Non-gravitational forces; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Theoretical Astrophysics; teoretisk astrofysik;

   Sammanfattning : Comets are the most primordial and least evolved bodies in the Solar System. As such, they are unique sources of information regarding the early history of the Solar System. However, little is known about cometary nuclei since they are very difficult to observe due to the obscuring coma. LÄS MER

4. 3. Quasar host galaxies at intermediate and high redshifts

   Författare :Eva Örndahl; Bengt Gustafsson; Jari Kotilainen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Active galaxies; Quasars; Host galaxies; Imaging; Photometry; Magnitudes; Colours; Morphology; Statistical methods; High-redshift; Infrared; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Theoretical Astrophysics; teoretisk astrofysik;

   Sammanfattning : Quasars form one of the most energetic phenomena in the universe, and can be traced out to very large redshifts. By studying the galaxies which host the active nuclei, important insights can be gained into the processes that trigger and maintain the quasar powerhouse. LÄS MER

5. 4. Laboratory and stellar spectroscopy of the complex ions Fe+, Mo+, Th+ and U+

   Författare :Hampus Nilsson; Astronomi - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; molybdenum; iron; thorium; uranium.; Atomic and molecular physics; Atom- och molekylärfysik; Astronomy; space research; cosmic chemistry; Astronomi; rymdvetenskap; kosmisk kemi; Condensed matter:electronic structure; electrical; spektroskopi; magnetisk resonans; supraledare; magnetiska och optiska ; egenskaper elektriska; Kondenserade materiens egenskaper:elektronstruktur; spectroscopy; relaxation; magnetic resonance; magnetic and optical properties; supraconductors; astrophysics; radiative lifetimes; oscillator strengths; term analysis; Fourier transform spectroscopy; branching fractions; Fysicumarkivet A:2002:Nilsson;

   Sammanfattning : The new generation of high resolution astronomical instruments such as the Hubble Space Telescope (HST) or the Very Large Telescope (VLT) has renewed the demand for accurate atomic parameters like wavelengths, oscillator strengths and line profiles accompanied by reliable uncertainty estimates. Fourier transform spectroscopy has proven to be a powerful tool when measuring these parameters. LÄS MER

7. 5. Radio waves in the ionosphere : Propagation, generation and detection

   Författare :Tobia Carozzi; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space Physics; rymdfysik;

   Sammanfattning : We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma. LÄS MER