Searching for hot magnetic flux ropes prior to major eruptions from disk regions

In some flares on or near the limb, AIA 131 A images show a distinct feature below a closed structure in 171 A images that appears to become the front of a coronal mass ejection (CME). As presented by several authors, this feature in 131 A channel may signal a hot magnetic flux rope seen in the Fe XXI line. It may correspond in disk view to an S-shaped loop before the eruption. But AIA (or SUVI) 131 A images alone may not serve as evidence for the presence of a hot flux rope because they are also contributed by cooler plasma in, e.g., Fe VIII lines. In order to further evaluate the importance of a hot flux rope in major eruptions that lead to full-blown CMEs, we compare IRIS Fe XXI (at 1354.08 A) spectra with AIA 131 A images for the intervals that precede and contain several disk events, eruptive or non-eruptive, in which the slit covers the area between the flare ribbons. We examine the IRIS spectra and eruptive properties of the events in which there is clear Fe XXI emission observed by IRIS before the eruption.