Very narrow coronal mass ejections producing solar energetic particles

¹ Astronomical Observatory of JU, Orla 171, Krakow, Poland
e-mail: katarzyna.bronarska@o2.pl
² Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
³ NASA Goddard Space Flight Center, Greenbelt, USA

Received: 15 April 2018
Accepted: 1 July 2018

Abstract

Aims. Our main aim is to study the relationship between low-energy solar particles (energies below 1 MeV) and very narrow coronal mass ejections (“jets” with angular width ≤ 20°).

Methods. For this purpose, we considered 125 very narrow coronal mass ejections (CMEs) from 1999 to 2003 that are potentially associated with low-energy solar particles (LESPs). These events were chosen on the basis of their source location. We studied only very narrow CMEs at the western limb, which are expected to have good magnetic connectivity with Earth.

Results. We found 24 very narrow CMEs associated with energetic particles such as ions (protons and ³He), electrons, or both. We show that arrival times at Earth of energetic particles are consistent with onset times of the respective CMEs, and that in the same time intervals, there are no other potential sources of energetic particles. We also demonstrate statistical differences for the angular width distributions using the Kolmogorov–Smirnov test for angular widths for these 24 events. We consider a coherent sample of jets (mostly originating from boundaries of coronal holes) to identify properties of events that produce solar energetic particles (velocities, widths, and position angles). Our study presents a new approach and result: very narrow CMEs can generate low-energy particles in the vicinity of Earth without other activity on the Sun. The results could be very useful for space weather forecasting.