P53E-2193
Evidence for a Bow Shock at Ceres?
Friday, 18 December 2015
Poster Hall (Moscone South)
Michaela Nicole Villarreal1, Christopher Russell2, Thomas H Prettyman3, Naoyuki Yamashita4, Ying-Dong Jia1 and Peter J Chi1, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)Russian Academy of Sciences, Moscow, Russia, (3)Planetary Science Institute, Albuquerque, NM, United States, (4)Planetary Science Institute Tucson, Tucson, AZ, United States
Abstract:
During Dawn’s Survey orbit, previously undetected spikes appeared in the +Z phoswich of Dawn’s Gamma Ray and Neutron Detector (GRaND) for a 10 day period from June 17th-June 27th, 2015. The spikes were seen in electron energies below 100 keV during a period, but not confined to, the arrival of energetic particles from active region AR2371. The spikes were separated by regular time intervals when the spacecraft was on the dayside of the planet. The spikes were consecutively located closer to the planet as the spacecraft approached the subsolar point. The dramatic increase in electron counts could be explained by the acceleration of the electrons at a Ceres bow shock. The dependence of the location of the spikes with relation to the subsolar point is consistent with a bow shock geometry. If a bow shock is confirmed, this would have considerable implications for the density of the Ceres exosphere during periods of high solar activity.
