Forward modelling of heating within a coronal arcade

Fyfe, Lianne; Howson, Thomas; Moortel, I. De

doi:10.1051/0004-6361/202142028

Cited by 2 publications

(1 citation statement)

References 27 publications

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“…While we find bursty heating events associated with reconnection after the buildup of magnetic energy over timescales of the order of ten minutes, this does not exclude that waves are also present. Fyfe et al (2021) compare synthesized spectra for simulations driven by differ-ent characteristic timescales associated with DC and AC heating, respectively. They find no observable difference between AC and DC runs for the location of the energy release.…”

Section: Heatingmentioning

confidence: 99%

A coronal loop in a box: From energy generation to coronal emission

Breu¹

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Vortex flows have been found in the photosphere, chromosphere and low corona in observations and simulations. It has been suggested that vortices play an important role for channelling energy and plasma into the corona, but the impact of vortex flows on the corona has not directly been studied in a realistic setup. We investigate the role vortices play for coronal heating using high resolution simulations of coronal loops. We perform 3D resistive MHD simulations with the MURaM code. Studying an isolated coronal loop in a Cartesian geometry allows us to resolve the structure of the loop interior. We conduct a statistical analysis to determine vortex properties as a function of height from the chromosphere into the corona. We find that the energy injected into the loop is generated by internal coherent motions within strong magnetic elements. A significant part of the resulting Poynting flux is channelled through the chromosphere in vortex tubes forming a magnetic connection between the photosphere and corona. Vortices can form contiguous structures that reach up to coronal heights, but in the corona itself the vortex tubes get deformed and eventually lose their identity with increasing height. Vortices show increased upward directed Poynting flux and heating rate both in the chromosphere and corona, but their effect becomes less pronounced with increasing height. While vortices play an important role for the energy transport and structuring in the chromosphere and low corona, their importance decreases higher up in the atmosphere. Vortex tubes reaching the corona show a complex relationship with the coronal emission.

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Section: Heatingmentioning

confidence: 99%

A coronal loop in a box: From energy generation to coronal emission

Breu¹

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The effects of driving time scales on coronal heating in a stratified atmosphere

Howson

Moortel

2022

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Aims. We investigate the atmospheric response to coronal heating driven by random velocity fields with different characteristic time scales and amplitudes. Methods. We conducted a series of three-dimensional magnetohydrodynamic simulations of random driving imposed on a gravitationally stratified model of the solar atmosphere. In order to understand differences between alternating current (AC) and direct current (DC) heating, we considered the effects of changing the characteristic time scales of the imposed velocities. We also investigated the effects of the magnitude of the velocity driving.Results. In all cases, complex foot point motions lead to a proliferation of current sheets and energy dissipation throughout the coronal volume. For a given driving amplitude, DC driving typically leads to a greater rate of energy injection when compared to AC driving. This ultimately leads to the formation of larger currents, increased heating rates and higher coronal temperatures in DC simulations. There is no difference in the spatial distribution of energy dissipation across simulations, however, energy release events in AC cases tend to be more frequent and last for less time than in DC cases. This results in more asymmetric temperature profiles for field lines heated by AC drivers. Higher velocity driving is associated with larger currents, higher temperatures and the corona occupying a larger fraction of the simulation volume. In all cases, the majority of heating is associated with small energy release events, which occur much more frequently than larger events. Conclusions. When combined with observational results that highlight a greater abundance of oscillatory power in lower frequency modes, these findings suggest that energy release in the corona is more likely to be driven by longer time scale motions. In the corona, AC and DC driving will occur concurrently and their effects remain difficult to isolate. The distribution of field line temperatures and the asymmetry of temperature profiles may reveal the frequency and longevity of energy release events and therefore the relative importance of AC and DC heating.

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Forward modelling of heating within a coronal arcade

Cited by 2 publications

References 27 publications

A coronal loop in a box: From energy generation to coronal emission

A coronal loop in a box: From energy generation to coronal emission

The effects of driving time scales on coronal heating in a stratified atmosphere

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