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End date: 2009 × Start date: 2000 × DDC: 530 × WGL Institute: AIP ×

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    Kinetic slow mode-type solitons
    (Göttingen : Copernicus GmbH, 2005) Baumgärtel, K.; Sauer, K.; Dubinin, E.
    One-dimensional hybrid code simulations are presented, carried out in order both to study solitary waves of the slow mode branch in an isotropic, collisionless, medium-β plasma (βi=0.25) and to test the fluid based soliton interpretation of Cluster observed strong magnetic depressions (Stasiewicz et al., 200; Stasiewicz, 2004) against kinetic theory. In the simulations, a variety of strongly oblique, large amplitude, solitons are seen, including solitons with Alfvenic polarization, similar to those predicted by the Hall-MHD theory, and robust, almost non-propagating, solitary structures of slow magnetosonic type with strong magnetic field depressions and perpendicular ion heating, which have no counterpart in fluid theory. The results support the soliton-based interpretation of the Cluster observations, but reveal substantial deficiencies of Hall-MHD theory in describing slow mode-type solitons in a plasma of moderate beta.
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    Mitwirkung des AIP am Betrieb des XMM-Newton Survey Science Center : Abschlussbericht ; Laufzeit: 1.1.2002 - 31.7.2008
    (Hannover : Technische Informationsbibliothek (TIB), 2008) Schwope, Axel; Lamer, Georg
    [no abstract available]
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    Die Verarbeitung des Rohdatenflusses eines Weltrauminterferometers : Schlussbericht zur Studie ; Zeitraum: 1.3.2000 - 31.12.2001
    (Potsdam : Leibniz-Institut für Astrophysik, 2002) Hirte, Sonja; Scholz, Ralf-Dieter; Schilbach, E.
    [no abstract available]
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    Starspots
    (Berlin : Springer Verlag, 2009) Strassmeier, K.G.
    Starspots are created by local magnetic fields on the surfaces of stars, just as sunspots. Their fields are strong enough to suppress the overturning convective motion and thus block or redirect the flow of energy from the stellar interior outwards to the surface and consequently appear as locally cool and therefore dark regions against an otherwise bright photosphere (Biermann in Astronomische Nachrichten 264:361, 1938; Z Astrophysik 25:135, 1948). As such, starspots are observable tracers of the yet unknown internal dynamo activity and allow a glimpse into the complex internal stellar magnetic field structure. Starspots also enable the precise measurement of stellar rotation which is among the key ingredients for the expected internal magnetic topology. But whether starspots are just blown-up sunspot analogs, we do not know yet. This article is an attempt to review our current knowledge of starspots. A comparison of a white-light image of the Sun (G2V, 5 Gyr) with a Doppler image of a young solar-like star (EK Draconis; G1.5V, age 100 Myr, rotation 10 × Ω Sun) and with a mean-field dynamo simulation suggests that starspots can be of significantly different appearance and cannot be explained with a scaling of the solar model, even for a star of same mass and effective temperature. Starspots, their surface location and migration pattern, and their link with the stellar dynamo and its internal energy transport, may have far reaching impact also for our understanding of low-mass stellar evolution and formation. Emphasis is given in this review to their importance as activity tracers in particular in the light of more and more precise exoplanet detections around solar-like, and therefore likely spotted, host stars. © 2009 Springer-Verlag.
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    Automatische Mustererkennunng dispergierter Interferenzbilder : Schlussbericht zur Studie
    (Potsdam : Leibniz-Institut für Astrophysik, 2001) Scholz, Ralf-Dieter; Schilbach, E.
    [no abstract available]
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    Shell models for Hall effect induced magnetic turbulence
    (College Park, MD : Institute of Physics Publishing, 2007) Frick, P.; Stepanov, R.; Rheinhardt, M.
    The Hall effect occurs in strongly magnetized conductive media and results in non-dissipative currents perpendicular to the electric field. We discuss its influence on the magnetic field dynamics ignoring fluid motion and ambipolar diffusion. The magnetic field evolution can then be basically similar to that of the velocity field in hydrodynamic turbulence resulting in a magnetic turbulence. Shell models for the induction equation with Hall effect are constructed on the basis of the conservation of magnetic energy and helicity in the dissipation-free limit. Numerical simulations of these models indicate that a magnetic energy cascade does occur, but the time behaviour and spatial spectrum of the magnetic field are very different from those of the velocity in shell models of hydrodynamic turbulence. ©IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
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    Vorhaben: Untersuchung von Teilchenbeschleunigungsmechanismen an Stoßwellen mittels der Daten des EPAC-Instruments an Bord des ULYSSES-Satelliten
    (Potsdam : Leibniz-Institut für Astrophysik, 2000) Mann, Gottfried
    [no abstract available]
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    Vorhaben: KORONAS/SORS-Satellitenprojekt (Radiospektrographie) : Schlussbericht
    (Potsdam : Leibniz-Institut für Astrophysik, 2001) Mann, G.
    [no abstract available]
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    Entwurf, Bau und Betrieb eines hochauflösenden optischen Spektralpolarimeters für das LBT - Large Binocular Telescope in Arizona : Schlussbericht für das BMBF-Vorhaben
    (Hannover : Technische Informationsbibliothek (TIB), 2008) Strassmeier, K.G.
    [no abstract available]