Spatial Relationship between Solar Flares and Coronal Mass Ejections

TL;DR

This study analyzes the spatial relationship between solar flares and coronal mass ejections over a decade, revealing that flare locations vary by class and are often centered within CMEs, supporting magnetic reconnection models.

Contribution

It provides a detailed long-term analysis of flare-CME spatial relationships, highlighting class-dependent flare positions and challenging previous conclusions about flare site distribution.

Findings

X-class flares often at CME center

C-class flares spread outside CME span

Supports magnetic reconnection eruption models

Abstract

We report on the spatial relationship between solar flares and coronal mass ejections (CMEs) observed during 1996-2005 inclusive. We identified 496 flare-CME pairs considering limb flares (distance from central meridian > 45 deg) with soft X-ray flare size > C3 level. The CMEs were detected by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). We investigated the flare positions with respect to the CME span for the events with X-class, M-class, and C-class flares separately. It is found that the most frequent flare site is at the center of the CME span for all the three classes, but that frequency is different for the different classes. Many X-class flares often lie at the center of the associated CME, while C-class flares widely spread to the outside of the CME span. The former is different from previous studies, which concluded that no preferred flare site exists. We compared our result with the previous studies and conclude that the long-term LASCO observation enabled us to obtain the detailed spatial relation between flares and CMEs. Our finding calls for a closer flare-CME relationship and supports eruption models typified by the CSHKP magnetic reconnection model.