The Nature of CME-Flare Associated Coronal Dimming

TL;DR

This study investigates the relationship between coronal dimming, CMEs, and flares using multi-instrument observations, revealing how dimming signatures reflect CME expansion and early eruption properties.

Contribution

It provides a detailed analysis of coronal dimming in relation to CME dynamics and flare activity, offering new insights into the early phases of CME eruptions.

Findings

Dimming occurs near flare ribbons and in multiple EUV passbands.

Dimming evolution correlates with CME height and flare reconnection rate.

Deep dimming cores rapidly grow and scale linearly with CME expansion.

Abstract

Coronal mass ejections (CMEs) are often accompanied by coronal dimming evident in extreme ultraviolet (EUV) and soft X-ray observations. The locations of dimming are sometimes considered to map footpoints of the erupting flux rope. As the emitting material expands in the corona, the decreased plasma density leads to reduced emission observed in spectral and irradiance measurements. Therefore, signatures of dimming may reflect properties of CMEs in the early phase of its eruption. In this study, we analyze the event of flare, CME, and coronal dimming on December 26, 2011. We use the data from the Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatories (SDO) for disk observations of the dimming, and analyze images taken by EUVI, COR1, and COR2 onboard the Solar Terrestrial Relations Observatories to obtain the height and velocity of the associated CMEs observed at the limb. We also measure magnetic reconnection rate from flare observations. Dimming occurs in a few locations next to the flare ribbons, and it is observed in multiple EUV passbands. Rapid dimming starts after the onset of fast reconnection and CME acceleration, and its evolution well tracks the CME height and flare reconnection. The spatial distribution of dimming exhibits cores of deep dimming with a rapid growth, and their light curves are approximately linearly scaled with the CME height profile. From the dimming analysis, we infer the process of the CME expansion, and estimate properties of the CME.