SH53A-2458
Low Solar Wind Density Causing the Fast Coronal Mass Ejection from 23 July 2012
Friday, 18 December 2015
Poster Hall (Moscone South)
Manuela Temmer, University of Graz, Graz, Austria and Nariaki Nitta, Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United States
Abstract:
The fast coronal mass ejection (CME) from July 23, 2012 raised special attention due to its short propagation time of less than 21hrs from Sun to 1 AU. In-situ data from STEREO-A revealed the arrival of a fast forward shock having a velocity of more than 2200 km/s followed by a magnetic structure with a speed of almost 1900 km/s. We study the evolution of the CME in interplanetary (IP) space using the drag based model to reproduce the short propagation time and high impact speed as derived from in-situ data. We find that the ambient density must have been exceptionally low due to which the drag force is reduced such that the CME experienced almost no deceleration. The density is found to be rather low due to the weak solar activity and was lowered even more by a previous CME event.
