Coronal Mini-jets in an Activated Solar Tornado-like Prominence

TL;DR

This study analyzes small, dynamic coronal jets from a solar tornado-like prominence using high-resolution IRIS data, revealing their physical properties, thermal nature, and likely magnetic reconnection origins, with implications for solar eruption mechanisms.

Contribution

First detailed statistical analysis of mini-jets in a tornado-like prominence, characterizing their physical parameters and proposing magnetic reconnection as their formation mechanism.

Findings

Mini-jets have lengths of 1.0-6.0 Mm and lifetimes of 10-50 s.

Jets are multi-thermal with an average temperature of ~2.6×10^5 K.

Reconnection events likely produce the mini-jets, influencing prominence stability.

Abstract

High-resolution observations from the $Interface~Region~Imaging~Spectrometer$ ($IRIS$) reveal the existence of a particular type of small solar jets, which arose singly or in clusters from a tornado-like prominence suspended in the corona. In this study, we perform a detailed statistical analysis of 43 selected mini-jets in the tornado event. Our results show that the mini-jets typically have: (1) a projected length of 1.0-6.0 Mm, (2) a width of 0.2-1.0 Mm, (3) a lifetime of 10-50 s, (4) a velocity of 100-350 km s$^{-1}$, and (5) an acceleration of 3-20 km s$^{-2}$. Based on spectral diagnostics and EM-Loci analysis, these jets seem to be multi-thermal small-scale plasma ejections with an estimated average electron density of $\sim$2.4 $\times$ 10$^{10}$ cm$^{-3}$ and an approximate mean temperature of $\sim$2.6 $\times$ 10$^{5}$ K. Their mean kinetic energy density, thermal energy density and dissipated magnetic field strength are roughly estimated to be $\sim$9 erg cm$^{-3}$, 3 erg cm$^{-3}$, and 16 G, respectively. The accelerations of the mini-jets, the UV and EUV brightenings at the footpoints of some mini-jets, and the activation of the host prominence suggest that the tornado mini-jets are probably created by fine-scale external or internal magnetic reconnections (a) between the prominence field and the enveloping or background field or (b) between twisted or braided flux tubes within the prominence. The observations provide insight into the geometry of such reconnection events in the corona and have implications for the structure of the prominence magnetic field and the instability that is responsible for the eruption of prominences and coronal mass ejections.