Analysis and study of the in situ observation of the June 1st 2008 CME by STEREO

作者：Nieves Chinchilla T^*; Gomez Herrero R; Vinas A F; Malandraki O; Dresing N; Hidalgo M A; Opitz A; Sauvaud J A; Lavraud B; Davila J M

来源：Journal of Atmospheric and Solar-Terrestrial Physics, 2011, 73(11-12): 1348-1360.

DOI：10.1016/j.jastp.2010.09.026

• Coronal mass ejection
• Magnetic cloud
• Solar wind
• Energetic particles

In this work we present a combined study of the counterpart of the coronal mass ejection (CME) of June 1st of 2008 in the interplanetary medium. This event has been largely studied because of its peculiar initiation and its possible forecasting consequences for space weather. We show an in situ analysis (on days June 6th-7th of 2008) of the CME in the interplanetary medium in order to shed some light on the propagation and evolution mechanisms of the interplanetary CME (ICME). The goals of this work are twofold: gathering the whole in situ data from PLASTIC and IMPACT onboard STEREO B in order to provide a complete characterization of the ICME, and to present a model where the thermal plasma pressure is included. The isolated ICME features show a clear forward shock which we identify as an oblique forward fast shock accelerating ions to a few-hundred key during its passage. Following the shock, a flux rope is easily defined as a magnetic cloud (MC) by the magnetic field components and magnitude, and the low proton plasma-beta. During the spacecraft passage through the MC, the energetic ion intensity shows a pronounced decrease, suggesting a closed magnetic topology, and the suprathermal electron population shows a density and temperature increase, demonstrating the importance of the electrons in the MC description. The in situ evidence suggests that there is no direct magnetic connection between the forward shock and the MC, and the characteristics of the reverse shock determined suggest that the shock pair is a consequence of the propagation of the ICME in the interplanetary medium. The energetic ions measured by the SEPT instrument suggest that their enhancement is not related to any solar event, but is solely due to the interplanetary shock consistent with the fact that no flares are observed on the Sun. The changes in the polarity of the interplanetary magnetic field in the vicinity of the ICME observed by electron PADs from SWEA are in accordance with the idea that the CME originated along a neutral line over the quiet Sun.
The magnetic cloud model presented in this work provides the plasma pressure as a new factor to consider in the study of the expansion and evolution of CMEs in the interplanetary medium. This model could provide a new understanding of the Sun-Earth connection because of the important role that the plasma plays in the eruption of the CME in the solar corona and the reconnection process carried out with the Earth's magnetosphere.

• 出版日期2011-7