First Measurements of Jovian Electrons by Parker Solar Probe/ISOIS Within 0.5 AU of the Sun

Authors: J. Grant Mitchell (George Washington University & NASA/GSFC), R. A. Leske (California Institute of Technology), G. A. de Nolfo (NASA/GSFC), E. R. Christian (NASA/GSFC), M. E. Wiedenbeck (Jet Propulsion Laboratory & California Institute of Technology), D. J. McComas (Princeton University), C. M. S. Cohen (California Institute of Technology), A. C. Cummings (California Institute of Technology), M. E. Hill (JHU/APL), A. W. Labrador (California Institute of Technology), M. L. Mays (NASA/GSFC), R. L. McNutt Jr. (JHU/APL), R. A. Mewaldt (California Institute of Technology), D. G. Mitchell (JHU/APL), D. Odstricil (George Mason University & NASA/GSFC), N. A. Schwadron (University of New Hampshire), E. C. Stone (California Institute of Technology), J. R Szalay (Princeton University)

Energetic electrons (MeV) emanating from the Jovian magnetosphere have been observed throughout the heliosphere, as far as 11 astronomical units (au), and as close as 0.5 au, from the Sun.  Studies indicate that Jovian electrons are a dominant source of energetic electrons in the heliosphere outside of solar energetic particle events.  The treatment of Jupiter as a continuously emitting point source of energetic electrons has made Jovian electrons a valuable tool in the study of energetic electron transport.  We present observations of Jovian electrons measured by the EPI-Hi instrument in the Integrated Science Investigation of the Sun (ISOIS) instrument suite on Parker Solar Probe at heliocentric distances within 0.5 au.  These are the closest measurements of Jovian electrons to the Sun.  We also find periods of nominal connection between the spacecraft and Jupiter in which expected Jovian electron enhancements are absent.  Several explanations for these absent events are explored, including stream interaction regions (SIRs) between Jupiter and Parker Solar Probe and the spacecraft being located on the opposite side of the heliospheric current sheet from Jupiter, both of which could impede the flow of the electrons.  These observations provide an opportunity to gain a greater insight into electron transport through a previously unexplored region of the inner heliosphere.