Supra-arcade downflows

Solar flare observed by TRACE 195 Å on 2002 April 21. SADs can be seen at center frame–note the dark "tadpoles" descending toward the bright coronal loop arcade.

Supra-arcade downflows (SADs) are sunward-traveling plasma voids that are sometimes observed in the Sun's outer atmosphere, or corona, during solar flares. In solar physics, arcade refers to a bundle of coronal loops, and the prefix supra indicates that the downflows appear above flare arcades. They were first described in 1999 using the Soft X-ray Telescope (SXT) on board the Yohkoh satellite.[1] SADs are byproducts of the magnetic reconnection process that drives solar flares, but their precise cause remains unknown.

  1. ^ McKenzie, D. E.; Hudson, H. S. (1999-07-01). "X-Ray Observations of Motions and Structure above a Solar Flare Arcade". The Astrophysical Journal. 519 (1): L93–L96. Bibcode:1999ApJ...519L..93M. CiteSeerX 10.1.1.42.5132. doi:10.1086/312110. S2CID 7360429.