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An Interface Region Imaging Spectrograph First View on Solar Spicules
Golub, L.; Tian, H.; De Pontieu, B. +17 more
Solar spicules have eluded modelers and observers for decades. Since the discovery of the more energetic type II, spicules have become a heated topic but their contribution to the energy balance of the low solar atmosphere remains unknown. Here we give a first glimpse of what quiet-Sun spicules look like when observed with NASA's recently launched…
Formation of a Double-decker Magnetic Flux Rope in the Sigmoidal Solar Active Region 11520
Cheng, X.; Ding, M. D.; Zhang, J. +5 more
In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observ…
Imaging and Spectroscopic Observations of a Filament Channel and the Implications for the Nature of Counter-streamings
Chen, P. F.; Harra, L. K.; Fang, C.
The dynamics of a filament channel are observed with imaging and spectroscopic telescopes before and during the filament eruption on 2011 January 29. The extreme ultraviolet (EUV) spectral observations reveal that there are no EUV counterparts of the Hα counter-streamings in the filament channel, implying that the ubiquitous Hα counter-streamings …
The Radiated Energy Budget of Chromospheric Plasma in a Major Solar Flare Deduced from Multi-wavelength Observations
Chamberlin, Phillip C.; Milligan, Ryan O.; Kerr, Graham S. +7 more
This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form of nonthermal electrons. Hard X-ray observations from RHESSI were used to track the evolution of the paramete…
The Solar Internetwork. I. Contribution to the Network Magnetic Flux
Gošić, M.; Bellot Rubio, L. R.; Katsukawa, Y. +2 more
The magnetic network (NE) observed on the solar surface harbors a sizable fraction of the total quiet Sun flux. However, its origin and maintenance are not well known. Here we investigate the contribution of internetwork (IN) magnetic fields to the NE flux. IN fields permeate the interior of supergranular cells and show large emergence rates. We u…
Magnetohydrodynamic Simulation of the X2.2 Solar Flare on 2011 February 15. I. Comparison with the Observations
Choe, G. S.; Park, Y. D.; Inoue, S. +2 more
We performed a magnetohydrodynamic (MHD) simulation using a nonlinear force-free field (NLFFF) in solar active region 11158 to clarify the dynamics of an X2.2-class solar flare. We found that the NLFFF never shows the dramatic dynamics seen in observations, i.e., it is in a stable state against the perturbations. On the other hand, the MHD simulat…
Simulating the Formation of a Sigmoidal Flux Rope in AR10977 from SOHO/MDI Magnetograms
Green, L. M.; Gibb, G. P. S.; Mackay, D. H. +1 more
The modeling technique of Mackay et al. is applied to simulate the coronal magnetic field of NOAA active region AR10977 over a seven day period (2007 December 2-10). The simulation is driven with a sequence of line-of-sight component magnetograms from SOHO/MDI and evolves the coronal magnetic field though a continuous series of non-linear force-fr…
Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like Prominence
Gan, Weiqun; Temmer, Manuela; Veronig, Astrid +5 more
Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However…
Thermal Structure of Current Sheets and Supra-arcade Downflows in the Solar Corona
Reeves, Katharine K.; Hanneman, Will J.
After the peak intensity of many large solar flares, magnetic and thermodynamic processes give rise to a phenomenon known as supra-arcade downflows (SADs). SADs are sunward flowing density depletions, often observed in post-flare plasma sheets. Some models have suggested that the plasma in the dark lanes is heated to temperatures of 20-80 MK, whic…
Physical Properties of White-light Sources in the 2011 February 15 Solar Flare
Fletcher, L.; Kerr, G. S.
White-light flares (WLFs) are observational rarities, making them understudied events. However, optical emission is a significant contribution to flare energy budgets and the emission mechanisms responsible could have important implications for flare models. Using Hinode SOT optical continuum data taken in broadband red, green, and blue filters, w…