Coronal Heating, Solar Filament Formation

Filament Channels: Isolated Laboratories of Plasma Heating in the Solar Corona

Comments Off on Filament Channels: Isolated Laboratories of Plasma Heating in the Solar Corona 01 December 2015

Abstract

Solar filament channels are complex systems comprising photospheric, chromospheric and coronal components. These components include magnetic neutral lines, supergranule cells, fibrils (spicules), filaments (prominences when observed on the limb), coronal cells, filament cavities and their overlying coronal arcades. Filaments are very highly structured and extend in height from the photosphere to the corona. Filament cores have chromospheric temperatures – 10,000 K (even at coronal heights ~ 100 Mm), surrounded by hotter plasma with temperature up to ~50,000 K. The whole filament is isolated from the rest of the solar corona by an envelope – the filament channel cavity – with temperatures of about 2,000,000 K. The filament channel cavity is even hotter than the solar corona outside the filament channel arcade. The compactness and big temperature variations make filament channels unique ready-to-go laboratories of coronal plasma heating and thermodynamics. In this work we discuss possible sources and mechanisms of heating in the filament channel environment. In particular, we address the mechanisms of magnetic canceling and current sheet dissipation.

Solar Filament Formation

Apparent Solar Tornado-Like Prominences

Comments Off on Apparent Solar Tornado-Like Prominences 01 February 2014

Abstract

Recent high-resolution observations from the Solar Dynamics Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado-like prominences. This class of prominences was first introduced by Pettit (Astrophys. J. 76, 9, 1932), who studied them over many years. Observations of tornado prominences similar to the ones seen by SDO had already been documented by Secchi (Le Soleil, 1877). High-resolution and high-cadence multiwavelength data obtained by SDO reveal that the tornado-like appearance of these prominences is mainly an illusion due to projection effects. We discuss two different cases where prominences on the limb might appear to have a tornado-like behavior. One case of apparent vortical motions in prominence spines and barbs arises from the (mostly) 2D counterstreaming plasma motion along the prominence spine and barbs together with oscillations along individual threads. The other case of apparent rotational motion is observed in a prominence cavity and results from the 3D plasma motion along the writhed magnetic fields inside and along the prominence cavity as seen projected on the limb. Thus, the “tornado” impression results either from counterstreaming and oscillations or from the projection on the plane of the sky of plasma motion along magnetic-field lines, rather than from a true vortical motion around an (apparent) vertical or horizontal axis. We discuss the link between tornado-like prominences, filament barbs, and photospheric vortices at their base.

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Featured Publications

  2016 (1)
Rapid Reconnection and Field Line Topology. Parker, E.; and Rappazzo, A. In Gonzalez, W.; and Parker, E., editor(s), Astrophysics and Space Science Library, volume 427, pages 181, 2016.
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  2015 (1)
Observations and Analysis of the Non-Radial Propagation of Coronal Mass Ejections Near the Sun. Liewer, P.; Panasenco, O.; Vourlidas, A.; and Colaninno, R. \solphys, 290: 3343-3364. November 2015.
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  2014 (1)
Apparent Solar Tornado-Like Prominences. Panasenco, O.; Martin, S.; and Velli, M. \solphys, 289: 603-622. February 2014.
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