Observations of instability-driven nanojets

Abstract

The recent discovery of nanojets by Antolin et al. (2021) represents magnetic reconnection in a braided field, thus clearly identifying the reconnection-driven nanoflares. Due to their small scale (500 km in widths, 1500 km in lengths) and short timescales ($<$ 15 s), it is unclear how pervasive nanojets are in the solar corona. In this paper, we present IRIS and SDO observations of nanojets found in multiple coronal structures, namely in a coronal loop powered by a blowout jet, and in two other coronal loops with coronal rain. In agreement with previous findings, we observe that nanojets are accompanied by small nanoflare-like intensity bursts in the (E)UV, have velocities of 150-250 km s${}^{-1}$ and occur transversely to the field line of origin, which is sometimes observed to split. However, we find a variety of nanojet directions in the plane transverse to the loop axis. These nanojets are found to have kinetic and thermal energies within the nanoflare range, and often occur in clusters. In the blowout jet case study, the Kelvin-Helmholtz instability (KHI) is directly identified as the reconnection driver. For the other two loops, we find that both, the KHI and the Rayleigh-Taylor instability (RTI) are likely to be the drivers. However, we find that the KHI and RTI are each more likely in one of the other two cases. These observations of nanojets in a variety of structures and environments support nanojets being a general result of reconnection, that are driven here by dynamic instabilities.

Accepted for publication in ApJ

References in corpus (18)

• Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions
• Coronal heating by MHD waves
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• A Breakout Model for Solar Coronal Jets with Filaments
• The discovery of geomagnetically trapped cosmic ray antiprotons
• Kelvin-Helmholtz instability in solar chromospheric jets: theory and observation
• The passband integrationproperties of Birefringent filter
• Coronal rain in magnetic bipolar weak fields
• Observing the formation of flare-driven coronal rain
• The First 3D Coronal Loop Model Heated by MHD Waves against Radiative Losses
• Multi-layered Kelvin-Helmholtz Instability in the Solar Corona
• An Analytical Model of the Kelvin-Helmholtz Instability of Transverse Coronal Loop Oscillations
• Coronal Mini-jets in an Activated Solar Tornado-like Prominence
• Transition to turbulence in nonuniform coronal loops driven by torsional Alfven waves
• Kelvin-Helmholtz instability on coronal mass ejecta in the lower corona
• Modelling of asymmetric nanojets in coronal loops
• Magnetic field inference in active region coronal loops using coronal rain clumps
• The Possibility of Kelvin-Helmholtz Instability in Solar Spicules

Cited by in corpus (7)

• Solar coronal heating from small-scale magnetic braids
• Temperature of Solar Orbiter/EUI quiet Sun small scale brightenings: evidence for a cooler component
• Hi-C 2.1 Observations of Reconnection Nanojets
• Coronal energy release by MHD avalanches III. Identification of a reconnection outflow from a nanoflare
• Merging plasmoids and nanojet-like ejections in a coronal current sheet
• Moving Plasma Structures and Possible Driving Mechanisms of Solar Microflares Observed with High-Resolution Coronal Imaging
• Pre-flare and active region plasma flows and structure seen by the short wavelength camera on SOLAR-C/EUVST