Energetic Particle Observations from Parker Solar Probe using Combined Energy Spectra from the IS$\odot$IS Instrument Suite

Abstract

The Integrated Science Investigations of the Sun (IS$\odot$IS) instrument suite includes two Energetic Particle instruments: EPI-Hi, designed to measure ions from ~1-200 MeV/nuc, and EPI-Lo, designed to measure ions from ~20 keV/nuc to ~15 MeV/nuc. We present an analysis of eight energetic proton events observed across the energy range of both instruments during PSP's first two orbits in order to examine their combined energy spectra. Background corrections are applied to help resolve spectral breaks between the two instruments and are shown to be effective. In doing so we demonstrate that, even in the early stages of calibration, IS$\odot$IS is capable of producing reliable spectral observations across broad energy ranges. In addition to making groundbreaking measurements very near the Sun, IS$\odot$IS also characterizes energetic particle populations over a range of heliocentric distances inside 1 au. During the first two orbits, IS$\odot$IS observed energetic particle events from a single corotating interaction region (CIR) at three different distances from the Sun. The events are separated by two Carrington rotations and just 0.11 au in distance, however the relationship shown between proton intensities and proximity of the spacecraft to the source region shows evidence of the importance of transport effects on observations of energetic particles from CIRs. Future IS$\odot$IS observations of similar events over larger distances will help disentangle the effects of CIR-related acceleration and transport. We apply similar spectral analyses to the remaining five events, including four that are likely related to stream interaction regions (SIRs) and one solar energetic particle (SEP) event.

Accepted for publication in the Astrophysical Journal Supplement Series

References in corpus (4)

• Energetic Particle Increases Associated with Stream Interaction Regions
• Observations of the 2019 April 4 Solar Energetic Particle Event at the Parker Solar Probe
• Seed Population Pre-Conditioning and Acceleration Observed by Parker Solar Probe
• CME -Associated Energetic Ions at 0.23 AU -- Consideration of the Auroral Pressure Cooker Mechanism Operating in the Low Corona as a Possible Energization Process

Cited by in corpus (5)

• The Solar Orbiter mission -- Science overview
• Energetic Particle Increases Associated with Stream Interaction Regions
• Observations of the 2019 April 4 Solar Energetic Particle Event at the Parker Solar Probe
• A Self-consistent Simulation of Proton Acceleration and Transport Near a High-speed Solar Wind Stream
• Parker Solar Probe observations of solar energetic particle (SEP) events with inverse velocity arrival (IVA) features