Speaker
Description
First Name: Benoit
Last Name: Lavraud
Affiliation: Laboratoire d'Astrophysique de Bordeaux
All Authors: B. Lavraud, N. Fargette, V. Génot, R. Kieokaew, C. Rasser, E. Buchlin, A. Fedorov, P. Louarn, V. Réville, A. P. Rouillard, N. André, M. Rojo, N. Aunai, L. Z. Hadid, S. Toledo-Redondo, T.-D. Phan, G. Kinoshita, B. Sanchez-Cano, L. Prech, R. Bruno, J. M. Raines, S. A. Livi, C. J. Owen, T. S. Horbury, M. Maksimovic, D. Schmid, W. Baumjohann, A. Matsuoka, D. Fischer, W. Magnes, H.-U. Auster, D. Heyner, and C. Lee
Abstract: Coronal mass ejections (CME) interact with their surrounding during lift-off in the corona as well as during their propagation in the interplanetary medium. CMEs may also interact with other CMEs if they are released in sequence, and closely separated in space and time. Scenarios where the interaction leads to the merging of sequential CMEs have been modelled using global simulations, but direct observation of this merging from two vantage points at different distances has not been reported so far. We present observations from the Solar Orbiter – Wind and BepiColombo – STEREO-A spacecraft pairs, in radial alignments at separate longitudes, which permit to study such interactions. Although the CMEs at both longitudes look alike, analysis of the helicity sign suggests they are different CMEs. A focus on measurements along the Solar Orbiter – Earth line shows signatures consistent with the merging of two CMEs. While two apparently distinct CMEs, with a compressed sheath region in between, are observed at Solar Orbiter close to the Sun (at 0.45 AU), only an apparent single CME is observed near Earth at Wind. Analysis suggests that the CME near Earth is in fact made of two CMEs after merging. Solar observations as well as in situ flux ropes orientations, suprathermal electron properties and magnetic reconnection signatures at both locations support this scenario.