An Observational Study of a “Rosetta Stone” Solar Eruption

This Letter reports observations of an event that connects all major classes of solar eruptions: those that erupt fully into the heliosphere versus those that fail and are confined to the Sun, and those that eject new flux into the heliosphere, in the form of a flux rope, versus those that eject only new plasma in the form of a jet. The event originated in a filament channel overlying a circular polarity inversion line and occurred on 2013 March 20 during the extended decay phase of the active region designated NOAA 12488/12501. The event was especially well observed by multiple spacecraft and exhibited the well-studied null-point topology. We analyze all aspects of the eruption using Solar Dynamics Observatory Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager, Solar-Terrestrial Relations Observatory Extreme Ultraviolet Imager, and Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph (SOHO LASCO) imagery. One section of the filament undergoes a classic failed eruption with cool plasma subsequently draining onto the section that did not erupt, but a complex structured coronal mass ejection/jet is clearly observed by SOHO/LASCO C2 shortly after the failed filament eruption. We describe in detail the slow buildup to eruption, the lack of an obvious trigger, and the immediate reappearance of the filament after the event. The unique mixture of major eruption properties observed during this event places severe constraints on the structure of the filament channel field and, consequently, on the possible eruption mechanism.