Fine Structures and Overlying Loops of Confined Solar Flares

Abstract

Using the Hα observations from the New Vacuum Solar Telescope at the Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped Hα fibrils. There exists a reconnection between the small loops, and thus the Hα fibrils change their configuration. The reconnection also occurs between a set of emerging Hα fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote positive faculae, forming a typical three-legged structure. During the flare processes, the overlying loops, some of which are tracked by activated dark materials, do not break out. These direct observations may illustrate the physical mechanism of confined flares, i.e., magnetic reconnection between the emerging loops and the pre-existing loops triggers flares and the overlying loops prevent the flares from being eruptive.

Enhancement of a Sunspot Light Wall With External Disturbances

“…We suggest that, although no obvious material flow along the bright channel was found, some amount of ejected material may still reach the light bridge. A somewhat similar process has been reported briefly by Yang et al (2014). In that study, on three homologous confined flares, one remote region brightened when each flare occurred, which is also deemed to be caused by ejected material.…”

Are Complex Magnetic Field Structures Responsible for the Confined X-class Flares in Super Active Region 12192?

“…Indeed there are some large-scale coronal loops above confined flares are observed (Yang et al 2014). However, the complex flare loops may also play a key role, but it is always omitted.…”

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

“…Sympathetic flares have been extensively reported and investigated in the past decades (e.g. Hanaoka, 1996;Lang & Willson, 1989;Masson et al, 2009;Wang & Liu, 2012;Deng et al, 2013;Sun et al, 2013;Yang et al, 2014;Liu et al, 2015a). The possible agents of energy transported from the source region of energy release to the remote footpoints are nonthermal electrons (Tang & Moore, 1982;Nakajima et al, 1985;Martin & Svestka, 1988), thermal conduction front (Rust et al, 1985;Bastian & Gary , 1992), shock waves (Machado et al , 1988), and reconnection outflows (Hanaoka, 1996;Nishio et al, 1997).…”