Sun: particle emission

A new method to determine solar energetic particle anisotropies and their associated uncertainties demonstrated for STEREO/SEPT

*Context.* The shape of the pitch-angle distribution (PAD) of solar energetic particles (SEPs) can be used to infer information about their source and interplanetary transport. In modeling and observational studies of SEP events, these PADs are …

The relativistic solar particle event on 28 October 2021: Evidence of particle acceleration within and escape from the solar corona

*Aims.* We analyse particle, radio, and X-ray observations during the first relativistic proton event of solar cycle 25 detected on Earth. The aim is to gain insight into the relationship between relativistic solar particles detected in space and the …

The first widespread solar energetic particle event of solar cycle 25 on 2020 November 29. Shock wave properties and the wide distribution of solar energetic particles

*Context.* On 2020 November 29, an eruptive event occurred in an active region located behind the eastern solar limb as seen from Earth. The event consisted of an M4.4 class flare, a coronal mass ejection, an extreme ultraviolet (EUV) wave, and a …

First near-relativistic solar electron events observed by EPD onboard Solar Orbiter

*Context.* Solar Orbiter, launched in February 2020, started its cruise phase in June 2020, in coincidence with its first perihelion at 0.51 au from the Sun. The in situ instruments onboard, including the Energetic Particle Detector (EPD), operate …

First year of energetic particle measurements in the inner heliosphere with Solar Orbiter's Energetic Particle Detector

*Context.* Solar Orbiter strives to unveil how the Sun controls and shapes the heliosphere and fills it with energetic particle radiation. To this end, its Energetic Particle Detector (EPD) has now been in operation, providing excellent data, for …

The first widespread solar energetic particle event observed by Solar Orbiter on 2020 November 29

*Context.* On 2020 November 29, the first widespread solar energetic particle (SEP) event of solar cycle 25 was observed at four widely separated locations in the inner (≲1 AU) heliosphere. Relativistic electrons as well as protons with energies 50 …

The long period of $^3$He-rich solar energetic particles measured by Solar Orbiter 2020 November 17-23

We report observations of a relatively long period of 3He-rich solar energetic particles (SEPs) measured by Solar Orbiter. The period consists of several well-resolved ion injections. The high-resolution STEREO-A imaging observations reveal that the …

The unusual widespread solar energetic particle event on 2013 August 19. Solar origin and particle longitudinal distribution

*Context.* Late on 2013 August 19, STEREO-A, STEREO-B, MESSENGER, Mars Odyssey, and the L1 spacecraft, spanning a longitudinal range of 222° in the ecliptic plane, observed an energetic particle flux increase. The widespread solar energetic particle …