TY - GEN A1 - Su, Yingna A1 - Kliem, Bernhard A1 - van Ballegooijen, Adriaan A1 - Deluca, Edward T1 - Numerical simulations of the CME on 2010 April 8 T2 - Solar and Astrophysical Dynamos and Magnetic Activity N2 - We present 3D zero-beta ideal MHD simulations of the solar flare/CME event that occurred in Active Region 11060 on 2010 April 8. The initial magnetic configurations of the two simulations are stable nonlinear force-free field and unstable magnetic field models constructed by Su et al. (2011) using the flux rope insertion method. The MHD simulations confirm that the stable model relaxes to a stable equilibrium, while the unstable model erupts as a CME. Comparisons between observations and MHD simulations of the CME are also presented. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 674 KW - Sun: coronal mass ejections (CMEs) KW - Sun: flares KW - Sun: magnetic fields Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-414887 SN - 1866-8372 IS - 674 SP - 575 EP - 576 ER - TY - JOUR A1 - Thompson, W. T. A1 - Kliem, Bernhard A1 - Toeroek, Tibor T1 - 3D reconstruction of a rotating erupting prominence JF - Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics N2 - A bright prominence associated with a coronal mass ejection (CME) was seen erupting from the Sun on 9 April 2008. This prominence was tracked by both the Solar Terrestrial Relations Observatory (STEREO) EUVI and COR1 telescopes, and was seen to rotate about the line of sight as it erupted; therefore, the event has been nicknamed the "Cartwheel CME." The threads of the prominence in the core of the CME quite clearly indicate the structure of a weakly to moderately twisted flux rope throughout the field of view, up to heliocentric heights of 4 solar radii. Although the STEREO separation was 48A degrees, it was possible to match some sharp features in the later part of the eruption as seen in the 304 line in EUVI and in the H alpha-sensitive bandpass of COR1 by both STEREO Ahead and Behind. These features could then be traced out in three-dimensional space, and reprojected into a view in which the eruption is directed toward the observer. The reconstructed view shows that the alignment of the prominence to the vertical axis rotates as it rises up to a leading-edge height of a parts per thousand aEuro parts per thousand 2.5 solar radii, and then remains approximately constant. The alignment at 2.5 solar radii differs by about 115A degrees from the original filament orientation inferred from H alpha and EUV data, and the height profile of the rotation, obtained here for the first time, shows that two thirds of the total rotation are reached within a parts per thousand aEuro parts per thousand 0.5 solar radii above the photosphere. These features are well reproduced by numerical simulations of an unstable moderately twisted flux rope embedded in external flux with a relatively strong shear field component. KW - Corona, active KW - Prominences, active KW - Coronal mass ejections KW - Initiation and propagation KW - Magnetic fields, corona Y1 - 2012 U6 - https://doi.org/10.1007/s11207-011-9868-5 SN - 0038-0938 VL - 276 IS - 1-2 SP - 241 EP - 259 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Liu, Rui A1 - Kliem, Bernhard A1 - Toeroek, Tibor A1 - Liu, Chang A1 - Titov, Viacheslav S. A1 - Lionello, Roberto A1 - Linker, Jon A. A1 - Wang, Haimin T1 - Slow rise and partial eruption of a double-decker filament. I. observations and interpretation JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We study an active-region dextral filament that was composed of two branches separated in height by about 13 Mm, as inferred from three-dimensional reconstruction by combining SDO and STEREO-B observations. This "double-decker" configuration sustained for days before the upper branch erupted with a GOES-class M1.0 flare on 2010 August 7. Analyzing this evolution, we obtain the following main results. (1) During the hours before the eruption, filament threads within the lower branch were observed to intermittently brighten up, lift upward, and then merge with the upper branch. The merging process contributed magnetic flux and current to the upper branch, resulting in its quasi-static ascent. (2) This transfer might serve as the key mechanism for the upper branch to lose equilibrium by reaching the limiting flux that can be stably held down by the overlying field or by reaching the threshold of the torus instability. (3) The erupting branch first straightened from a reverse S shape that followed the polarity inversion line and then writhed into a forward S shape. This shows a transfer of left-handed helicity in a sequence of writhe-twist-writhe. The fact that the initial writhe is converted into the twist of the flux rope excludes the helical kink instability as the trigger process of the eruption, but supports the occurrence of the instability in the main phase, which is indeed indicated by the very strong writhing motion. (4) A hard X-ray sigmoid, likely of coronal origin, formed in the gap between the two original filament branches in the impulsive phase of the associated flare. This supports a model of transient sigmoids forming in the vertical flare current sheet. (5) Left-handed magnetic helicity is inferred for both branches of the dextral filament. (6) Two types of force-free magnetic configurations are compatible with the data, a double flux rope equilibrium and a single flux rope situated above a loop arcade. KW - Sun: coronal mass ejections (CMEs) KW - Sun: filaments, prominences KW - Sun: flares Y1 - 2012 U6 - https://doi.org/10.1088/0004-637X/756/1/59 SN - 0004-637X VL - 756 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Teriaca, Luca A1 - Andretta, Vincenzo A1 - Auchere, Frederic A1 - Brown, Charles M. A1 - Buchlin, Eric A1 - Cauzzi, Gianna A1 - Culhane, J. Len A1 - Curdt, Werner A1 - Davila, Joseph M. A1 - Del Zanna, Giulio A1 - Doschek, George A. A1 - Fineschi, Silvano A1 - Fludra, Andrzej A1 - Gallagher, Peter T. A1 - Green, Lucie A1 - Harra, Louise K. A1 - Imada, Shinsuke A1 - Innes, Davina A1 - Kliem, Bernhard A1 - Korendyke, Clarence A1 - Mariska, John T. A1 - Martinez-Pillet, Valentin A1 - Parenti, Susanna A1 - Patsourakos, Spiros A1 - Peter, Hardi A1 - Poletto, Luca A1 - Rutten, Robert J. A1 - Schuehle, Udo A1 - Siemer, Martin A1 - Shimizu, Toshifumi A1 - Socas-Navarro, Hector A1 - Solanki, Sami K. A1 - Spadaro, Daniele A1 - Trujillo-Bueno, Javier A1 - Tsuneta, Saku A1 - Dominguez, Santiago Vargas A1 - Vial, Jean-Claude A1 - Walsh, Robert A1 - Warren, Harry P. A1 - Wiegelmann, Thomas A1 - Winter, Berend A1 - Young, Peter T1 - LEMUR large european module for solar ultraviolet research JF - Experimental astronomy : an international journal on astronomical instrumentation and data analysis N2 - The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 and 1270 . The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s (-aEuro parts per thousand 1) or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. KW - Sun: atmosphere KW - Space vehicles: instruments KW - Techniques: spectroscopy KW - ESA cosmic vision Y1 - 2012 U6 - https://doi.org/10.1007/s10686-011-9274-x SN - 0922-6435 VL - 34 IS - 2 SP - 273 EP - 309 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Kliem, Bernhard A1 - Török, Tibor A1 - Thompson, William T. T1 - A parametric study of erupting flux rope rotation modeling the "Cartwheel CME" on 9 April 2008 JF - Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics N2 - The rotation of erupting filaments in the solar corona is addressed through a parametric simulation study of unstable, rotating flux ropes in bipolar force-free initial equilibrium. The Lorentz force due to the external shear-field component and the relaxation of tension in the twisted field are the major contributors to the rotation in this model, while reconnection with the ambient field is of minor importance, due to the field's simple structure. In the low-beta corona, the rotation is not guided by the changing orientation of the vertical field component's polarity inversion line with height. The model yields strong initial rotations which saturate in the corona and differ qualitatively from the profile of rotation vs. height obtained in a recent simulation of an eruption without preexisting flux rope. Both major mechanisms writhe the flux rope axis, converting part of the initial twist helicity, and produce rotation profiles which, to a large part, are very similar within a range of shear-twist combinations. A difference lies in the tendency of twist-driven rotation to saturate at lower heights than shear-driven rotation. For parameters characteristic of the source regions of erupting filaments and coronal mass ejections, the shear field is found to be the dominant origin of rotations in the corona and to be required if the rotation reaches angles of order 90 degrees and higher; it dominates even if the twist exceeds the threshold of the helical kink instability. The contributions by shear and twist to the total rotation can be disentangled in the analysis of observations if the rotation and rise profiles are simultaneously compared with model calculations. The resulting twist estimate allows one to judge whether the helical kink instability occurred. This is demonstrated for the erupting prominence in the "Cartwheel CME" on 9 April 2008, which has shown a rotation of a parts per thousand aEuro parts per thousand 115(a similar to) up to a height of 1.5 R (aS (TM)) above the photosphere. Out of a range of initial equilibria which include strongly kink-unstable (twist I broken vertical bar=5 pi), weakly kink-unstable (I broken vertical bar=3.5 pi), and kink-stable (I broken vertical bar=2.5 pi) configurations, only the evolution of the weakly kink-unstable flux rope matches the observations in their entirety. KW - Corona, active KW - Prominences, dynamics KW - Coronal mass ejections, initiation and propagation KW - Magnetic fields, corona KW - Magnetohydrodynamics Y1 - 2012 U6 - https://doi.org/10.1007/s11207-012-9990-z SN - 0038-0938 VL - 281 IS - 1 SP - 137 EP - 166 PB - Springer CY - Dordrecht ER -