Solar Eruptions

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Science  28 Apr 2000:
Vol. 288, Issue 5466, pp. 577
DOI: 10.1126/science.288.5466.577c

Coronal mass ejections are huge bubble-like pockets of gas that erupt from the solar corona in association with energetic filaments or flares. These ejections offer clues for understanding the transfer of energy into and out of the corona: a practical concern because coronal mass ejections can create geomagnetic disturbances that disrupt satellite communications and electrical power grids on Earth.

Using x-ray images from the Yohkoh soft x-ray telescope, Khan and Hudson observed events surrounding the disappearance of three transequatorial magnetic loops, structures that connect an active region in the north of the sun to an active region in the south. In each case, a solar flare ignited at one active region, emitting soft x-rays. As the x-rays moved outward from the flare, the magnetic loop fractured, and then a mass ejection occurred above the now discontinuous loop. The authors infer that the flare initiates a shock wave and that the shock wave causes the loop to rupture, leading to coronal mass ejection. Thus, coronal mass ejections may occur over loops instead of flares, and these large loops should be watched with care.—LR

Geophys. Res. Lett.27, 1083 (2000).

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