A Microfilament-Eruption Mechanism for Solar Spicules

Abstract

Recent investigations indicate that solar coronal jets result from eruptions of small-scale chromospheric filaments, called minifilaments; that is, the jets are produced by scaled-down versions of typical-sized filament eruptions. We consider whether solar spicules might in turn be scaled-down versions of coronal jets, being driven by eruptions of microfilaments. Assuming a microfilament's size is about a spicule's width (∼300 km), the estimated occurrence number plotted against the estimated size of erupting filaments, minifilaments, and microfilaments approximately follows a power-law distribution (based on counts of CMEs, coronal jets, and spicules), suggesting that many or most spicules could result from microfilament eruptions. Observed spicule-base Ca ii brightenings plausibly result from such microfilament eruptions. By analogy with coronal jets, microfilament eruptions might produce spicules with many of their observed characteristics, including smooth rise profiles, twisting motions, and EUV counterparts. The postulated microfilament eruptions are presumably eruptions of twisted-core micro magnetic bipoles that are ∼1 ′′ .0 wide. These explosive bipoles might be built and destabilized by merging and cancelation of magnetic-flux elements of ∼few×100 G and of size < ∼ 0 ′′ .5-1 ′′ .0. If however spicules are relatively more numerous than indicated by our extrapolated distribution, then only a fraction of spicules might result from this proposed mechanism.

Generation of solar spicules and subsequent atmospheric heating

“…Our results support the hypothesis that fast spicules originate from magnetic reconnection (14,20,21). It is possible that a sub-photospheric local dynamo mechanism (22) or magnetoconvection process (13,23) generates weak magnetic fields close to the large-scale network fields.…”

Two-fluid Numerical Simulations of Solar Spicules

“…Later, this rebound shock model was improved by including radiation and heat conduction in the model (e.g., Sterling & Mariska 1990;Cheng 1992;Sterling et al 1993;Heggland et al 2007;Kuźma et al 2017). Recently, Sterling & Moore (2016) have reported that the microfilament-eruptions can be a potential candidate for the generation of spicules. Murawski & Zaqarashvili (2010) performed 2D numerical simulations with a velocity pulse to produce the spicule.…”

Observation and Modeling of Solar Jets

“…Taken together with the results of Panesar et al [66][67][68] they also claim that flux cancellation is the main process whereby the energy is stored prior to eruption in all jets and CMEs, and may also be involved in the triggering process. So far, the finding of blowout jets has been confirmed by many observational studies, and now we recognized that the vast majority of solar jets are caused by magnetic flux cancellation rather than flux emergence [62,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84]. Recently, high resolution observational studies showed that two-sidedloop jets are also associated with flux cancellations and include the eruption of mini-filaments inside the base arches [43,46,49,85,86], and two-sided-loop jets occurring in filament channels may important for causing the eruption of large filaments [87].…”

“…Shen et al [62,69] studied two blowout jets and found that the erupting mini-filaments directly form the cool component of coronal jets (see Figure 2). Recently, more and more observational studies confirmed that blowout jets are driven by mini-filament eruptions or filament channels [73][74][75][76][77][78][79][80][81][82][83][84]97,98]; some authors even proposed that all coronal jets are originated from mini-filament eruptions, and their generation resembles the eruption of large-scale, energetic filament/CME eruptions [36,65,99].…”