The link between CMEs, filaments and filament channels

Abstract

Abstract. We present a broad concept for the build-up to eruptive solar events which needs to be tested in future observational and theoretical research. In this concept an eruptive solar event consists of a coronal mass ejection, a filament eruption, a cavity around the filament, and a flare. In our picture, the initial energy source must be external to this eruptive system but also feed into it. Among all eruptive events the common denominator is a filament channel with canceling magnetic fields along a primary polarity reversal boundary. We find that magnetic reconnection at or close to the photosphere is the only interpretation of canceling fields to date that is consistent with observations of filament channels. This reconnection serves to transfer magnetic flux from the photosphere into the chromosphere and corona along polarity reversal boundaries and concurrently initiates the building of a filament channel. Magnetic flux, in excess of that needed to sustain the filament channel, goes into building a filament magnetic field that is always aligned with the polarity reversal boundary and the channel magnetic field. The filament magnetic field remains separated from overarching coronal magnetic fields by the magnetic field of the cavity. The magnetic flux being transported upward from the photosphere/chromosphere carries streams of plasma into the corona along the filament magnetic field. However, the flowing and counterstreaming filament mass also slowly drains out of the field and thereby leaves behind new strands of cavity magnetic field with little or no associated mass. When the build-up of magnetic pressure in the filament and cavity magnetic fields exceeds that of the overlying coronal loops, the coronal loops, the filament and the cavity together begin an observable slow rise which can last a few hours to many days before rapid onset and ejection with a solar flare. We suggest that this process can be accelerated by any number of external triggering mechanisms which serve as catalysts Correspondence to: S. F. Martin (sara@helioresearch.org) to cause the impending eruption to happen earlier than it otherwise would occur.

Evidence for Mixed Helicity in Erupting Filaments

“…In that case, the helicity of the filament itself would be opposite in sign to that of the overlying coronal loops, contrary to most theoretical models. Possible support for this picture comes from the observation of continual flows along the spines and up and down the barbs of filaments (Zirker et al 1998;Wang 1999;Kucera et al 2003;Lin et al 2003Lin et al , 2005; such flows, which may be driven by chromospheric reconnection (Litvinenko & Martin 1999;Martin et al 2008), seem to obviate the need for static support within magnetic dips, one of the principal arguments in favor of a flux rope geometry.…”

Origins of Rolling, Twisting, and Non-radial Propagation of Eruptive Solar Events

“…Concurrently, rotational mass motions with the opposite signs of chirality (and helicity) in the two legs are observed to flow downward while the body of the filament ascends. However, in asymmetric eruptions, both legs are not always observed (Martin, 2003;Panasenco and Martin, 2008).…”

“…Cremades, Bothmer and Tripathi, 2006;Gopalswamy et al 2009;Kilpua et al, 2009;Zuccarello et al, 2012). Prominence deflection and rolling motion during eruptions received less attention, though there has been some work in the same general direction as advocated here (Filippov, Gopalswamy and Lozhechkin, 2001;Martin 2003;Panasenco and Martin, 2008;Bemporad 2009;Panasenco et al, 2011;Pevtsov, Panasenco and Martin, 2012;Liewer, Panasenco and Hall, 2012). The formation of the CME flux rope appears to occur in the early phase of filament eruption, when the rolling motion of the filament is already in progress (Liewer, Panasenco and Hall, 2012).…”

Comments on Magnetic Reconnection Models of Canceling Magnetic Features on the Sun

“…The observational term "cancellation" describes the disappearance of magnetic flux of either sign in such canceling magnetic features at the polarity inversion line that separates the fragments Martin et al 1985). Photospheric magnetic flux cancellation is interesting both in its own right and as a key process in the formation and evolution of solar filaments (Martens & Zwaan 2001;Martin et al 2008;Chae 2012;Panasenco et al 2014). Photospheric cancellation has been studied using the data from instruments on board several satellites, including Solar and Heliospheric Observatory (Chae et al 2002), Hinode (Park et al 2009), and Solar Dynamics Observatory (Zeng et al 2014).…”