A Microfilament-Eruption Mechanism for Solar Spicules

TL;DR

This paper proposes that solar spicules are driven by microfilament eruptions, similar to coronal jets but on a smaller scale, supported by observed correlations and plausible magnetic mechanisms.

Contribution

It introduces the microfilament eruption mechanism as a novel explanation for the origin of solar spicules, extending the filament eruption model to smaller scales.

Findings

Spicule occurrence follows a power-law distribution with filament sizes.

Ca II brightenings at spicule bases are consistent with microfilament eruptions.

Microfilament eruptions can produce observed spicule characteristics.

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 ($\sim$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 $\sim$1$".0$ wide. These explosive bipoles might be built and destabilized by merging and cancelation of magnetic-flux elements of $\sim$few$\times 100$~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.