Sunspot light-bridges - a bridge between the photosphere and the corona ?

TL;DR

This paper investigates how sunspot light-bridges connect the photosphere to the corona by analyzing their associated chromospheric activity, jets, and heating effects using multi-instrument observations.

Contribution

It provides new insights into the response of the transition region and lower corona to light-bridge activity through multi-instrument data analysis.

Findings

Light-bridges are linked to chromospheric jets and heating of coronal loops.

Reconnection processes may explain the observed activity.

Transition region and lower corona respond dynamically to light-bridge presence.

Abstract

Recent observations of sunspot light-bridges have shed new light on the fact that they are often associated with significant chromospheric activity. In particular chromospheric jets (Shimizu et al. 2009) persisting over a period of days have been identifies, sometimes associated with large downflows at the photospheric level (Louis et al. 2009). One possible explanation for this activity is reconnection low in the atmosphere. Light-bridges have also been associated with a constant brightness enhancement in the 1600 angstroms passband of TRACE, and the heating of 1 MK loops. Using data from EIS, SOT and STEREO EUVI we investigate the response of the transition region and lower corona to the presence of a light-bridge and specific periods of chromospheric activity.