Multiwavelength Study of Equatorial Coronal-hole Jets

Abstract

Jets (transient/collimated plasma ejections) occur frequently throughout the solar corona and contribute mass/energy to the corona and solar wind. By combining numerical simulations and high-resolution observations, we have made substantial progress recently on determining the energy buildup and release processes in these jets. Here we describe a study of 27 equatorial coronal-hole jets using Solar Dynamics Observatory/AIA and HMI observations on 2013 June 27-28 and 2014 January 8-10. Out of 27 jets, 18 (67%) are associated with mini-filament ejections; the other 9 (33%) do not show mini-filament eruptions but do exhibit mini-flare arcades and other eruptive signatures. This indicates that every jet in our sample involved a filament-channel eruption. From the complete set of events, 6 jets (22%) are apparently associated with tiny flux-cancellation events at the polarity inversion line, and 2 jets (7%) are associated with sympathetic eruptions of filaments from neighboring bright points. Potential-field extrapolations of the source-region photospheric magnetic fields reveal that all jets originated in the fan-spine topology of an embedded bipole associated with an extreme ultraviolet coronal bright point. Hence, all our jets are in agreement with the breakout model of solar eruptions. We present selected examples and discuss the implications for the jet energy build-up and initiation mechanisms.

First Detection of Plasmoids from Breakout Reconnection on the Sun

“…The properties of the blobs (size, temperature, etc.) were similar to those reported for the plasma blobs in previous AIA observations of flare current sheets (Takasao et al 2012;Kumar & Cho 2013;Kumar et al 2018Kumar et al , 2019. These jet observations also agree with results of the highest-resolution MHD simulations of breakout jets and CMEs, which consistently find that multiple plasmoids form in the breakout and flare current sheets (Karpen et al 2012;Guo et al 2013;Lynch & Edmondson 2013;Lynch et al 2016;Guidoni et al 2016).…”

“…No flare arcade was detected, however, which indicates minimal or no flare reconnection below the filament and thus no flux-rope formation along the PIL. We also interpret the brief appearance of bright spots at the base of the fan, far from the site where flare ribbons would occur, as evidence for particle acceleration on selected field lines comprising the fan surface (Sterling & Moore 2001;Kumar et al 2018). Finally, the bidirectional flows and plasma blobs (plasmoids) coming from the vicinity of the fan-spine intersection are unmistakable signs of magnetic reconnection.…”

Observation and modelling of solar jets

“…Shen et al [63,69] studied two blowout jets and found that the erupting mini-filaments directly form the cool component of coronal jets (figure 2). Recently, more and more observational studies have 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 originate from mini-filament eruptions, and their generation resembles the eruption of large-scale, energetic filament/CME eruptions [36,65,99].…”

“…Panesar et al [98] argued that the reason for flux emergence not directly causing jets is because the speed of emergence is seldom, if ever, fast enough. The emerging-reconnection scenario was challenged by the discovery of blowout jets that often involve the eruption of mini-filaments or filament channels [36,62,63,69,97] in association with flux cancellations [44,66,68,247,[304][305][306][307][308], and the cool component of blowout jets is actually the erupting filament material itself [44,63,69] rather than chromospheric material carried up by the emerging flux and accelerated by the show the direction of movement of the magnetic field lines, and features including the X-point, slow and fast shocks, and cool and hot jets are indicated [140].…”

“…magnetic tension force as proposed in the emerging-reconnection model [129]. In a statistical study of 27 equatorial coronal hole jets, Kumar et al [97] found that six jets (22%) were apparently associated with flux cancellations, while the remaining events did not show measurable flux emergence or cancellation associated with the eruption. Therefore, the ultimate trigger source of solar jets still requires further investigation.…”