Coronal energy release by MHD avalanches III. Identification of a reconnection outflow from a nanoflare
arXiv:2502.01796 · doi:10.1051/0004-6361/202452426
Abstract
Outflows perpendicular to the guide field are believed to be a possible signature of magnetic reconnection in the solar corona and specifically a way to detect the occurrence of ubiquitous small-angle magnetic reconnection. The aim of this work is to identify possible diagnostic techniques of such outflows in hot coronal loops with SDO/AIA and the forthcoming MUltislit Solar Explorer (MUSE), in a realistically dynamic coronal loop environment in which an MHD avalanche is occurring. We consider a 3D MHD model of two magnetic flux tubes, including a stratified, radiative and thermal-conducting atmosphere, twisted by footpoint rotation. The faster rotating flux tube becomes kink-unstable and soon involves the other one in the avalanche. The turbulent decay of this magnetic structure on a global scale leads to the formation, fragmentation, and dissipation of current sheets driving impulsive heating akin to a nanoflare storm. We captured a clear outflow from a reconnection episode soon after the initial avalanche and synthesized its emission as detectable with AIA and MUSE. The outflow has a maximum temperature around 8 MK, a total energy of 1024 erg, a velocity of a few hundred km/s, and a duration of less than 1 min. We show the emission in the AIA 94 A channel (Fe XVIII line) and in the MUSE 108 A Fe XIX spectral line. his outflow shares many features with nanojets recently detected at lower temperatures. Its low emission measure makes, however, its detection difficult with AIA, but Doppler shifts can be measured with MUSE. Conditions become different in a later steady state phase when the flux tubes are filled with denser and relatively cooler plasma.
12 pages, 12 figures; Accepted on Astronomy and Astrophysics
References in corpus (18)
- PLUTO: a Numerical Code for Computational Astrophysics
- CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
- Highly Efficient Modeling of Dynamic Coronal Loops
- Key Aspects of Coronal Heating
- Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
- The multi-thermal and multi-stranded nature of coronal rain
- Probing the physics of the solar atmosphere with the Multi-slit Solar Explorer (MUSE): I. Coronal Heating
- Microflare Heating of a Solar Active Region Observed with NuSTAR, Hinode/XRT, and SDO/AIA
- Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE): II. Flares and Eruptions
- 3D MHD modeling of twisted coronal loops
- IRIS observations of short-term variability in moss associated with transient hot coronal loops
- Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops
- NuSTAR observations of a repeatedly microflaring active region
- Observations of instability-driven nanojets
- Heating Mechanisms for Intermittent Loops in Active Region Cores from AIA/SDO EUV Observations
- Hi-C 2.1 Observations of Reconnection Nanojets
- A Statistical Study of IRIS Observational Signatures of Nanoflares and Non-thermal Particles
- Coronal energy release by MHD avalanches. Effects on a structured, active region, multi-threaded coronal loop