LASCO and EIT Observations of Helical Structure in Coronal Mass Ejections

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Abstract
Observations of coronal mass ejections (CMEs) by the Large Angle Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SOHO) show a significant fraction with circular intensity patterns. In the past, these would have been called "disconnection" events, but we suggest that these are evidence of CMEs containing helical magnetic flux ropes that are often central to many theoretical models of CMEs and have been observed in magnetic clouds near 1 AU. Three examples are examined in detail with the LASCO and Extreme-Ultraviolet Imaging Telescope (EIT) data sets, which provide observations from their initiation through 30 R☉.