Observations and modeling of the onset of fast reconnection in the solar transition region

Abstract

Magnetic reconnection is a fundamental plasma process that plays a critical role not only in energy release in the solar atmosphere, but also in fusion, astrophysical, and other space plasma environments. One of the challenges in explaining solar observations in which reconnection is thought to play a critical role is to account for the transition of the dynamics from a slow quasi-continuous phase to a fast and impulsive energetic burst of much shorter duration. Despite the theoretical progress in identifying mechanisms that might lead to rapid onset, a lack of observations of this transition has left models poorly constrained. High-resolution spectroscopic observations from NASA's Interface Region Imaging Spectrograph (IRIS) now reveal tell-tale signatures of the abrupt transition of reconnection from a slow phase to a fast, impulsive phase during UV bursts or explosive events in the Sun's atmosphere. Our observations are consistent with numerical simulations of the plasmoid instability, and provide evidence for the onset of fast reconnection mediated by plasmoids and new opportunities for remote-sensing diagnostics of reconnection mechanisms on the Sun.

9 pages, 5 figures, accepted for publication in Astrophysical Journal

References in corpus (8)

• Instability of current sheets and formation of plasmoid chains
• Hot Explosions in the Cool Atmosphere of the Sun
• General Theory of the Plasmoid Instability
• On the Distribution of Plasmoids In High-Lundquist-Number Magnetic Reconnection
• Plasmoid Instability in Evolving Current Sheets and Onset of Fast Reconnection
• Intermittent reconnection and plasmoids in UV bursts in the low solar atmosphere
• Ellerman bombs and UV bursts: transient events in chromospheric current sheets
• Onset of turbulent fast magnetic reconnection observed in the solar atmosphere

Cited by in corpus (13)

• Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE): II. Flares and Eruptions
• Capturing transient plasma flows and jets in the solar corona
• Ultra-high resolution observations of plasmoid-mediated magnetic reconnection in the deep solar atmosphere
• Pitch-Angle Anisotropy Imprinted by Relativistic Magnetic Reconnection
• Coalescence Instability in Chromospheric Partially Ionised Plasmas
• Multi-Fluid Simulations of Upper Chromospheric Magnetic Reconnection with Helium-Hydrogen mixture
• Collisional ionisation and recombination effects on coalescence instability in chromospheric partially ionised plasmas
• High flow speeds and transition-region like temperatures in the solar chromosphere during flux emergence
• A comparative study of resistivity models for simulations of magnetic reconnection in the solar atmosphere. II. Plasmoid formation
• Shocks and instabilities in the partially ionised solar atmosphere
• Extreme-ultraviolet (EUV) observables of simulated plasmoid-mediated reconnection in the solar corona
• A new view of the solar interface region from the Interface Region Imaging Spectrograph (IRIS)
• Emergence of internetwork magnetic fields through the solar atmosphere