A Multiwavelength Study of Eruptive Events on January 23, 2012 Associated with a Major Solar Energetic Particle Event

TL;DR

This study analyzes the solar eruptions on January 23, 2012, using multiwavelength data to understand their role in a major solar energetic particle event and subsequent geomagnetic storm.

Contribution

It provides a detailed multiwavelength analysis of two interacting CMEs and their impact on SEP flux and geomagnetic disturbances, highlighting CME interaction effects.

Findings

Two fast CMEs interacted near the Sun, influencing SEP intensity.

The compound CME caused a double-dip geomagnetic storm.

CME interaction may enhance SEP flux and geomagnetic effects.

Abstract

We use multiwavelength data from space and ground based instruments to study the solar flares and coronal mass ejections (CMEs) on January 23, 2012 that were responsible for one of the largest solar energetic particle (SEP) events of solar cycle 24. The eruptions consisting of two fast CMEs (1400 km/s and 2000 km/s) and M-class flares that occurred in active region 11402 located at N28 W36. The two CMEs occurred in quick successions, so they interacted very close to the Sun. The second CME caught up with the first one at a distance of 11-12 Rsun. The CME interaction may be responsible for the elevated SEP flux and significant changes in the intensity profile of the SEP event. The compound CME resulted in a double-dip moderate geomagnetic storm (Dst = -73 nT). The two dips are due to the southward component of the interplanetary magnetic field in the shock sheath and the ICME intervals. One possible reason for the lack of a stronger geomagnetic storm may be that the ICME delivered a glancing blow to Earth.