Open AccessThe origin and development of the May 1997 magnetic cloud
Author(s) -
Webb D. F.,
Lepping R. P.,
Burlaga L. F.,
DeForest C. E.,
Larson D. E.,
Martin S. F.,
Plunkett S. P.,
Rust D. M.
Publication year - 2000
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000ja000021
Subject(s) - magnetic cloud , coronal mass ejection , physics , ejecta , rope , solar wind , corona (planetary geology) , coronal cloud , astrophysics , interplanetary spaceflight , coronagraph , protein filament , coronal hole , flux (metallurgy) , magnetic flux , geophysics , astronomy , magnetic field , venus , astrobiology , planet , supernova , materials science , structural engineering , quantum mechanics , exoplanet , engineering , biology , metallurgy , genetics
A complete halo coronal mass ejection (CME) was observed by the SOHO Large‐Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May 12, 1997. It was associated with activity near Sun center, implying that it was aimed earthward. Three days later on May 15 an interplanetary shock and magnetic cloud/flux rope transient was detected at the Wind spacecraft 190 R E upstream of Earth. The long enduring southward magnetic fields associated with these structures triggered a geomagnetic storm. The CME was associated with a small coronal arcade that formed over a filament eruption with expanding double ribbons in H α emission. The flare was accompanied by a circular EUV wave, and the arcade was flanked by adjacent dimming regions. We surmise that these latter regions marked the feet of a flux rope that expanded earthward into the solar wind and was observed as the magnetic cloud at Wind. To test this hypothesis we determined key parameters of the solar structures on May 12 and compared them with the modeled flux rope parameters at Wind on May 15. The measurements are consistent with the flux rope originating in a large coronal structure linked to the erupting filament, with the opposite‐polarity feet of the rope terminating in the depleted regions. However, bidirectional electron streaming was not observed within the cloud itself, suggesting that there is not always a good correspondence between such flows and ejecta.