Tracing the signatures of a quiet Sun nanoflare

¹ Rosseland Centre for Solar Physics (RoCS), University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
e-mail: rebecrob@uio.no
² Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway

Received: 3 June 2023
Accepted: 13 July 2023

Abstract

Context. Nanoflare-scale reconnection events are difficult to detect, and even when they are detected, it is tricky to reconstruct the details and trigger mechanisms that power them. However, numerical models of nanoflare-scale reconnection can provide context to observations of small-scale reconnection events via the comparison of synthetic observables to observed signatures of the nanoflare.

Aims. We aim to demonstrate how a simulated nanoflare event would look if it were observed by the Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA) and the upcoming Multi-slit Solar Explorer (MUSE). The goal is to determine the details (if any) of nanoflare-scale reconnection events that could reasonably be captured by current and future instruments.

Methods. We calculated synthetic observables from a quiet Sun simulation of a nanoflare-scale reconnection event, including integrated intensities of Fe IX at 171.073 Å and Fe XII at 195.119 Å. Then, we degraded the synthetic observables to SDO/AIA and MUSE resolutions in order to determine whether the instruments are capable of capturing the details of the reconnection event.

Results. We determine that even small-scale reconnection events in the quiet Sun can be detected by both SDO/AIA and MUSE. In the 171 channel of each instrument, it is possible to discern details of the two bidirectional jets that emanate from the reconnection site. These two bidirectional jets correspond to two different magnetic features undergoing large-angle reconnection with an overlying horizontal field in the corona. In the 193 channel of SDO/AIA, it is only possible to see one set of bidirectional jets, which corresponds to the most energetic reconnecting feature. However, the calculated count rate for AIA 193 is not sufficient for a reliable observation.

Conclusions. Quiet Sun activity is detectable with SDO/AIA and will be detectable with the future MUSE mission. It is possible to detect bidirectional jets with both instruments, which can give context clues as to the mechanisms causing the nanoflare event. The resolution and spectral information of MUSE will give a much more detailed observation of the event, making it much easier to reconstruct a possible trigger mechanism. However, we must be careful in our interpretations of observations when we have limited information, as vastly different physical processes can produce similar observational signatures.