Coronal Dimming Associated with a Giant Prominence Eruption

Abstract

We report the results of our investigation of a giant eruptive prominence (initial mass ~6×1016 g) using microwave, X-ray, and white-light observations. The prominence erupted from the northwest limb of the Sun on 1994 April 5. The speed of the prominence was only ~70 km s−1 when it reached a height of ~0.5 R above the solar surface. In X-rays, a large region with reduced X-ray emission was observed enveloping the initial location of the prominence and extending to much larger heights. At the bottom of this depletion and beneath the eruptive prominence, an X-ray arcade formed, progressively spreading from south to north along the limb. This is the first time a direct detailed comparison is made between coronal dimming and a prominence eruption. We were able to confirm that the coronal dimming is indeed a near-surface manifestation of the coronal mass ejection (CME). The orientation of the structures involved did not allow the observations of the coronal cavity, but all the other substructures of the CME could be identified. The mass expelled from the Sun in the form of the eruptive prominence and the coronal dimming are comparable. The estimated total mass is somewhat larger than that reported in other X-ray-dimming events.