# Observational signatures of a kink-unstable coronal flux rope using Hinode/EIS

## TL;DR

This study uses forward modelling of 3D simulations to identify observable signatures of kink instability in coronal flux ropes with Hinode/EIS, highlighting detectable features like loop growth and Doppler shifts.

## Contribution

It demonstrates how synthetic Hinode/EIS observations can reveal signatures of kink instability in coronal flux ropes, advancing observational diagnostics.

## Key findings

- Detection of loop radius growth and intensity increase at the loop edge.
- Identification of Doppler velocity patterns consistent with twisted magnetic fields.
- EIS cannot resolve small-scale reconnection events like nanoflares.

## Abstract

The signatures of energy release and energy transport for a kink-unstable coronal flux rope are investigated via forward modelling. Synthetic intensity and Doppler maps are generated from a 3D numerical simulation. The CHIANTI database is used to compute intensities for three Hinode/EIS emission lines that cover the thermal range of the loop. The intensities and Doppler velocities at simulation resolution are spatially degraded to the Hinode/EIS pixel size (1\arcsec), convolved using a Gaussian point-spread function (3\arcsec), and exposed for a characteristic time of 50 seconds. The synthetic images generated for rasters (moving slit) and sit-and-stare (stationary slit) are analysed to find the signatures of the twisted flux and the associated instability. We find that there are several qualities of a kink-unstable coronal flux rope that can be detected observationally using Hinode/EIS, namely the growth of the loop radius, the increase in intensity towards the radial edge of the loop, and the Doppler velocity following an internal twisted magnetic field line. However, EIS cannot resolve the small, transient features present in the simulation, such as sites of small-scale reconnection (e.g. nanoflares)