Long‐duration neutron production by nonflaring transients in the solar corona

Abstract

The purpose of this work is to study neutron enhancements observed using the Neutron Spectrometer aboard MESSENGER in order to identify events that may have been generated at/or near the Sun by solar transients. To securely establish an origin of the observed neutrons that is nonlocal to the MESSENGER spacecraft, a measurement of the energetic ion environment local to MESSENGER is needed. For this purpose, we use energetic ion spectrometers on several spacecraft at 1 AU when they were magnetically connected to MESSENGER during an event. We report strong evidence that for six neutron events studied in detail, the detected neutrons do not likely have a local spacecraft origin. By implication, most of the detected neutrons for these six events may have originated near the Sun, generated by many moderate‐level solar eruptive events that produce an extended solar exosphere of moderate‐energy neutrons, protons, and electrons.

Galactic cosmic ray variations in the inner heliosphere from solar distances less than 0.5 AU: Measurements from the MESSENGER Neutron Spectrometer

“…Based on instrument modeling, this triple‐coincidence count rate measures the integral flux of protons and alpha particles greater than 125 MeV/nucleon and thus serves as a proxy for GCR flux for the vicinity around the MESSENGER spacecraft. To date, energetic particle data from the NS have been used to make corrections to neutron data measured during the first year of orbital operations [ Lawrence et al ., ] and to understand the interaction of charged particles with the MESSENGER spacecraft for studies of solar neutrons [ Feldman et al ., , ; Lawrence et al ., , ]. In addition, Rodgers et al .…”