Now showing items 1-8 of 8

    • Chromospheric and coronal activity - analysing optical spectra of M dwarfs 

      Fuhrmeister, Birgit (Univ. Hamburg, 2005)
      Unter stellarer Aktivität werden eine Reihe von Phänomenen in den unterschiedlichen Atmosphärenschichten zusammengefasst, die eng mit dem Magnetfeld des einzelnen Sterns verbunden sind. Da eine direkte Auflösung der ...
    • LINC-NIRVANA piston control and near-infrared polarization images of the Orion proplyds 

      Rost, Steffen (Univ. Köln, 2008)
      This thesis is focussed on the development of optimized techniques to overcome limitations of astrophysical observations. The goal is an optimal signal estimation in noisy measurements by the consideration of underlying ...
    • Multi-telescope studies of neutron stars 

      Lazaridis, Kosmas (Univ. Köln, 2009)
      Neutron stars are unique stellar remnants with extreme properties, as their density and magnetic field. Their study can be the key to a number of unanswered problems in fundamental physics and astronomy, ranging from stellar ...
    • The near infrared activity of Sagittarius A* 

      Meyer, Leonhard (Univ. Köln, 2008)
      The meaning of my thesis was to obtain new insights about the supermassive Black Hole in the center of our Milky Way and its accretion flow. The non-thermal radio, X-ray, and near-infrared source Sagittarius A* (Sgr A*) ...
    • Non-analytical line profiles in stellar atmospheres - for planetary host star systems 

      Johnas, Christine M. S. (Univ. Hamburg, 2008)
      In this work, nonanalytical line profiles for both cool and hot, dense atmospheres are added to the opacity calculations of the multipurpose stellar atmosphere code PHOENIX. Their influence on model atmospheres and synthetic ...
    • The spectral energy distribution of polars 

      Vogel, Justus (Univ. Berlin, 2008)
      Magnetic cataclysmic variables, also called AM Her stars or 'polars', are close binaries with mass transfer (accretion), consisting of a late-type main-sequence star (commonly called secondary)and a more massive white dwarf ...
    • The structure and spectra of irradiated secondaries in close binaries (pre-CVs) 

      Wawrzyn, Alexander Christopher (Univ. Hamburg, 2009)
      Many stars evolve not alone but along one or more companions. While the evolution of single isolated stars is well predicted by theoretical calculations, close binary systems with their interactions are on the one hand far ...
    • Surface spots on cool giant stars probed by spectro-astrometry 

      Voigt, Boris (Univ. Hamburg, 2009)
      Spectro-astrometry is a technique to obtain information about the structure of an astronomical source on sub-diffraction limited spatial scales down to milli- or micro-arcseconds. The method exploits the shift of the ...