Analysis of a coronal mass ejection and co-rotating interaction region as they travel from the Sun passing Venus, Earth, Mars and Saturn

摘要

During June 2010 a good alignment in the solar system between Venus, STEREO-B, Mars and Saturn provided an excellent opportunity to study the propagation of a Coronal Mass Ejection (CME) and closely occurring Co-rotating Interaction Region (CIR) from the Sun to Saturn. The CME erupted from the Sun at 01:30 UT on 20 June 2010, with v≈600 km s-1, as observed by STEREO-B, SDO and SOHO/LASCO. It arrived at Venus over 2 days later, some 3.5 days after a CIR is also detected here. The CIR was also observed at STEREO-B and Mars, prior to the arrival of the CME. The CME is not directed Earthward, but the CIR is detected here less than 2 days after its arrival at Mars. Around a month later, a strong compression of the Saturn magnetosphere is observed by Cassini, consistent with the scenario that the CME and CIR have merged into a single solar transient. The arrival times of both the CME and the CIR at different locations were predicted using the ENLIL with cone model. The arrival time of the CME at Venus, STEREO-B and Mars is predicted to within 20 hours of its actual detection, but the predictions for the CIR showed greater differences from observations, all over 1.5 days early. More accurate predictions for the CIR were found by extrapolating the travel time between different locations using the arrival times and speeds detected by STEREO-B and ACE. We discuss the implications of these results for understanding the propagation of solar transients.