Sökning: "photosphere"

Visar resultat 6 - 10 av 13 avhandlingar innehållade ordet photosphere.

1. 6. Atomic Influences in Stellar Spectroscopy

   Författare :Krister Nielsen; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetic and optical properties; supraconductors; magnetic resonance; relaxation; Kondenserade materiens egenskaper:elektronstruktur; spectroscopy; rymdvetenskap; kosmisk kemi; Astronomi; Astronomy; spektroskopi; magnetisk resonans; supraledare; magnetiska och optiska ; egenskaper elektriska; space research; cosmic chemistry; stellar magnetic fields; branching fractions; spectral line structure; Fysicumarkivet A:2002:Nielsen; Condensed matter:electronic structure; line blending; electrical;

   Sammanfattning : This thesis is a description of how knowledge of atomic physics can be used in a stellar spectrum analysis. Stellar investigations are spectroscopically performed based on wavelengths, intensities and spectral line structure. LÄS MER

3. 7. Circumstellar dust emission from nearby Solar-type stars

   Författare :Joachim Wiegert; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: binaries - Stars: circumstellar matter - Infrared: stars - Infrared: planetary systems - Submillimeter: stars;

   Sammanfattning : Far-infrared excess above the photosphere of a star indicates the presence of a circumstellar dust disc which is a sign-post for extrasolar planets, and was first detected in the mid 1980s. Dust discs are intricately connected to planets and planetesimals, give insights in the dynamics and evolution of the system, and are also useful for future exoplanet-observations. LÄS MER

4. 8. Constraining magnetic heating in the solar chromosphere

   Författare :Roberta Morosin; Jaime de la Cruz Rodríguez; Elena Khomenko; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; magnetic fields; spectropolarimetry; Astronomy; astronomi;

   Sammanfattning : The chromospheric and coronal heating problems remain one of the foremost open questions in solar and stellar physics: how are the outer layers of the Sun heated from a few thousand kelvin in the photosphere to the million-degree corona? Radiation alone is not capable of transporting the required energy to explain observations from the inner layers. Phenomena associated with the presence of magnetic fields could provide the missing energy. LÄS MER

5. 9. The dynamic chromosphere : Results and techniques with an observational approach

   Författare :Carolina Robustini; Jorrit Leenaarts; Fernando Moreno Insertis; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; jets; sunspots; imaging; spectropolarimetry; Astronomy; astronomi;

   Sammanfattning : The chromosphere is a critical interface between the relatively cold photosphere and the hot corona. Its landscape is rich in very dynamic phenomena such as jets, spicules, and surges, which are thought to play an important role in the heating of the Sun’s upper atmosphere. LÄS MER

7. 10. The synthetic chromosphere : Results and techniques with a numerical approach

   Författare :Johan Pires Bjørgen; Jorrit Leenaarts; Oskar Steiner; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; radiative transfer; numerical method; Astronomy; astronomi;

   Sammanfattning : Realistic numerical simulations of the solar atmosphere can be used to interpret different phenomena observed on the solar surface. To gain insight into the atmospheric physical conditions, we compare the observations with 3D radiative magnetohydrodynamic models combined with forward modeling (radiative transfer). LÄS MER