Analysis of Suprathermal Proton Events Observed by STEREO/PLASTIC Focusing on the Observation of Bow Shock/Magnetospheric Events

摘要

The topic of suprathermal and energetic ion events upstream of the Earth's bow shock has been investigated since the late 1960's. Over the past 50 years, these events have been characterized as having energies ranging from just above the solar wind energies on through 2MeV, time spans of minutes to hours, and particle distributions ranging from field aligned to isotropic. The seed particles of these events accelerated within the magnetosphere and/or at the Earth's bow shock have been shown to be of ions originating in the magnetosphere, solar wind, as well as ions energized in other heliospheric processes (such as solar energetic particle (SEP), corotating interaction regions (CIRs), Pick-up ions, etc.). In this study we utilize STEREO/PLASTIC to examine bow shock/magnetospheric energetic proton events observed throughout 2007 in the region far upstream of the Earth's ion foreshock. To do this, we first employ an automated procedure to identify suprathermal proton events in the energy range of 4keV up to 80keV. The occurrence of events, magnetic connection to the Earth, and Compton-Getting transformed energy spectra of 66 possible STA bow shock/magnetospheric events are investigated as a function of spacecraft-Earth separation.