Authors: P.S. Pathare, M. I. Desai., M. A. Dayeh, M. J. Starkey, & the ISOIS Science Team
Properties of Energetic Particles in the Sub-Alfvénic Solar Wind Flow Observed by Parker Solar Probe
- Pathare, M. I. Desai., M. A. Dayeh, M. J. Starkey, & the ISOIS Science Team
Coronal Mass Ejections (CMEs) can drive shock waves that accelerate particles to near-relativistic energies. CME-driven shocks are now considered the most prolific sources of Solar Energetic Particles (SEPs), which pose significant radiation hazards to our environment and our assets both on Earth and in space.
Sub-Alfvénic solar wind, characterized by speeds slower than the Alfvén speed, is magnetically dominated and observed closer to the Sun. From orbit 8 (beginning April 28, 2021), NASA’s Parker Solar Probe (PSP) began flying through this magnetically dominated corona, which is one of the mission’s primary objectives.
Here we survey the ion composition, spectral properties, and anisotropies of suprathermal-to-energetic particles during the time intervals when PSP sampled the sub-Alfvénic solar wind flow. We initiated this study by identifying time periods where the Alfvén speed exceeds the solar wind speed during each PSP perihelion in the magnetically-dominated corona. Subsequently, we analyze the spectral properties and ion composition of energetic particles during these time intervals. These particles could serve as candidate seed populations for CME-driven shocks that produce hazardous, large gradual solar energetic particle events.