Parallel plasma loops and the energization of the solar corona

Abstract

The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (<1 MK) loops seen in the core of an active region to address the role of field-line braiding in energising these structures. We report observations from the High-resolution Coronal imager (Hi-C) that have been acquired in a coordinated campaign with the Interface Region Imaging Spectrograph (IRIS). In the core of the active region, the 172 A band of Hi-C and the 1400 A channel of IRIS show plasma loops at different temperatures that run in parallel. There is a small but detectable spatial offset of less than 1 arcsec between the loops seen in the two bands. Most importantly, we do not see observational signatures that these loops might be twisted around each other. Considering the scenario of magnetic braiding, our observations of parallel loops imply that the stresses put into the magnetic field have to relax while the braiding is applied: the magnetic field never reaches a highly braided state on these length-scales comparable to the separation of the loops. This supports recent numerical 3D models of loop braiding in which the effective dissipation is sufficiently large that it keeps the magnetic field from getting highly twisted within a loop.

arXiv commentAccepted for publication in the Astrophysical Journal, 24 pages, 18 figures

References in corpus (34)

• The Interface Region Imaging Spectrograph (IRIS)
• Hot Explosions in the Cool Atmosphere of the Sun
• Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions
• CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite lines
• Extension of the MURaM radiative MHD code for coronal simulations
• Nonlinear Dynamics of the Parker Scenario for Coronal Heating
• On the generation of solar spicules and Alfvénic waves
• JHelioviewer - Time-dependent 3D visualisation of solar and heliospheric data
• Forward modeling of stellar coronae: from a 3D MHD model to synthetic EUV spectra
• Structure of solar coronal loops: from miniature to large-scale
• Coronal heating through braiding of magnetic field lines
• On red shifs in the transition region and corona
• Intermittent heating in the solar corona employing a 3D MHD model
• Transient small-scale brightenings in the quiet solar corona: a model for campfires observed with Solar Orbiter
• Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields
• Dynamics of braided coronal loops - I. Onset of magnetic reconnection
• Constant cross section of loops in the solar corona
• The High-Resolution Coronal Imager, Flight 2.1
• Evidence for Steady Heating: Observations of an Active Region Core with Hinode and TRACE
• Observationally driven 3D MHD model of the solar corona above an active region
• Magnetic reconnection at the earliest stage of solar flux emergence
• Fine-scale explosive energy release at sites of prospective magnetic flux cancellation in the core of the solar active region observed by Hi-C 2.1, IRIS and SDO
• A model for the formation of the active region corona driven by magnetic flux emergence
• Observations and numerical models of solar coronal heating associated with spicules
• Observational Signatures of Coronal Loop Heating and Cooling Driven by Footpoint Shuffling
• Amplitudes and energy fluxes of simulated decayless kink oscillations
• Trigger Mechanism of Solar Subflares in a Braided Coronal Magnetic Structure
• Wave heating in gravitationally stratified coronal loops in the presence of resistivity and viscosity
• Force-free field modeling of twist and braiding-induced magnetic energy in an active-region corona
• Data-driven model of the solar corona above an active region
• Magnetic Jam in the Corona of the Sun
• Using coronal seismology to estimate the magnetic field strength in a realistic coronal model
• Emergence of granular-sized magnetic bubbles through the solar atmosphere. III. The path to the transition region
• Plasma injection into a solar coronal loop