First Solar energetic particles measured on the Lunar far-side

Abstract

On 2019 May 6, the Lunar Lander Neutron & Dosimetry (LND) Experiment on board the Chang'E-4 on the far-side of the Moon detected its first small solar energetic particle (SEP) event with proton energies up to 21MeV. Combined proton energy spectra are studied based on the LND, SOHO/EPHIN and ACE/EPAM measurements which show that LND could provide a complementary dataset from a special location on the Moon, contributing to our existing observations and understanding of space environment. Velocity dispersion analysis (VDA) has been applied to the impulsive electron event and weak proton enhancement and the results demonstrate that electrons are released only 22 minutes after the flare onset and $\sim$15 minutes after type II radio burst, while protons are released more than one hour after the electron release. The impulsive enhancement of the in-situ electrons and the derived early release time indicate a good magnetic connection between the source and Earth. However, stereoscopic remote-sensing observations from Earth and STA suggest that the SEPs are associated with an active region nearly 100${}^{\circ }$ away from the magnetic footpoint of Earth. This suggests that the propagation of these SEPs could not follow a nominal Parker spiral under the ballistic mapping model and the release and propagation mechanism of electrons and protons are likely to differ significantly during this event.

arXiv commentApJ Letter

References in corpus (4)

• First observations of a dome-shaped large-scale coronal EUV wave
• Solar energetic particle access to distant longitudes through turbulent field-line meandering
• The Lunar Lander Neutron and Dosimetry (LND) Experiment on Chang'E 4
• Energetic Particle Observations from Parker Solar Probe using Combined Energy Spectra from the IS$\odot$IS Instrument Suite

Cited by in corpus (5)

• Primary and albedo protons detected by the Lunar Lander Neutron and Dosimetry (LND) experiment on the lunar farside
• Investigation of Inverse Velocity Dispersion in a Solar Energetic Particle Event Observed by Solar Orbiter
• Radial dependence of ion fluences in the 2023 July 17 SEP event from Parker Solar Probe to STEREO and ACE
• Anomalous cosmic rays within the inner heliosphere: Observations of helium by the High Energy Telescope onboard Solar Orbiter
• Parker Solar Probe observations of solar energetic particle (SEP) events with inverse velocity arrival (IVA) features