TY  - GEN
A1  - Driel-Gesztelyi, L. van
A1  - Baker, Daniel N.
A1  - Török, Tibor
A1  - Pariat, Etienne
A1  - Green, L. M.
A1  - Williams, D. R.
A1  - Carlyle, J.
A1  - Valori, G.
A1  - Démoulin, Pascal
A1  - Matthews, S. A.
A1  - Kliem, Bernhard
A1  - Malherbe, J.-M.
T1  - Magnetic reconnection driven by filament eruption in the 7 June 2011 event
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - During an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 608 
KW  - MHD
KW  - instabilities
KW  - Sun: activity
KW  - magnetic fields
KW  - coronal mass ejections (CMEs)
KW  - filaments
KW  - methods: numerical
KW  - data analysis
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-415671
IS  - 608
SP  - 502
EP  - 503
ER  - 
TY  - GEN
A1  - Seiß, Martin
A1  - Spahn, Frank
T1  - Hydrodynamics of Saturn’s dense rings
T2  - Postprints der Universität Potsdam : Postprint Mathematisch Naturwissenschaftliche Reihe
N2  - The space missions Voyager and Cassini together with earthbound observations re-vealed a wealth of structures in Saturn’s rings. There are, for example, waves being excited at ring positions which are in orbital resonance with Saturn’s moons. Other structures can be assigned to embedded moons like empty gaps, moon induced wakes or S-shaped propeller features. Further-more, irregular radial structures are observed in the range from 10 meters until kilometers. Here some of these structures will be discussed in the frame of hydrodynamical modeling of Saturn’s dense rings. For this purpose we will characterize the physical properties of the ring particle ensemble by mean field quantities and point to the special behavior of the transport coefficients. We show that unperturbed rings can become unstable and how diffusion acts in the rings. Additionally, the alternative streamline formalism is introduced to describe perturbed regions of dense rings with applications to the wake damping and the dispersion relation of the density waves.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 574 
KW  - granular gas
KW  - instabilities
KW  - hydrodynamics
KW  - planetary rings
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-413139
SP  - 191
EP  - 218
ER  - 
TY  - GEN
A1  - Oskinova, Lida
A1  - Feldmeier, Achim
A1  - Kretschmar, Peter
T1  - Clumped stellar winds in supergiant high-mass X-ray binaries
T2  - Postprint der universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the Bondi-Hoyle-Lyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. Photoionization of inhomogeneous winds is different from the photoinization of smooth winds. The degree of ionization is affected by the wind clumping. The wind clumping must also be taken into account when comparing the observed and model spectra of the photoionized stellar wind.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 573 
KW  - accretion
KW  - instabilities
KW  - stars: mass loss
KW  - X-rays: binaries
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-413916
SN  - 1866-8372
IS  - 573
SP  - 287
EP  - 288
ER  -