Expansion of coronal mass ejections from the low to the outer corona

CREMADES, H.; IGLESIAS, F. A.; MERENDA, L.A.; LÓPEZ, F.M.

San Juan

Congreso; Towards Future Research on Space Weather Drivers; 2019

Coronal mass ejections (CMEs) constitute the most spectacular dynamic events in the solar system, and are key players in determining space weather conditions. Given that the ocurrence of a CME has so far been impossible to predict, the best attempt at forecasting is to assess their impact with the best possible accuracy. In this respect, understanding how magnetic fields are organized within CMEs, and how they evolve from the low corona into the heliosphere, is crucial. Exceptional ongoing solar missions, such as STEREO, SOHO, and SDO, provide a unique opportunity to shed light into this aspect. The stereoscopic-view images provided by the STEREO/SECCHI suite in combination with images from Earth?s perspective recorded by SDO/AIA and SOHO/LASCO enable the analysis of CME evolution from their birth in the low corona. The set of CMEs uder study arises from an appropriate combination of spacecraft vantage points and CME propagation direction, which is helpful to reduce uncertainties in their forward modeling. These events are carefully analyzed as they originate low in the corona by means of simultaneous observations of STEREO/EUVI and SDO/AIA, and followed up to the outer fields of view of the STEREO and SOHO coronagraphs. In particular, we examine the evolution of their global magnetic field configuration, and how CMEs expand along the direction of their main symmetry axisand orthogonal to it.