Authors: Michael R. Collier, A. Szabo, W. Farrell, J.A. Slavin, R. P. Lepping, R. Fitzenreiter, B. Thompson, D. C. Hamilton, G. Gloeckler, G. Ho, P.
Bochsler, D. Larson, and L. Ofman
Reference: J. Geophys. Res., submitted, 1999
Abstract:
Evidence is presented that the WIND spacecraft observed particle and
field signatures resulting from the footpoints of the magnetic cloud of
October 18-19, 1995, reconnecting at a low altitude, between 1 and 5
solar radii. The observations include (i) an internal shock traveling
approximately along the axis of the magnetic cloud, (ii) simple
compression of the magnetic field consistent with the footpoint
magnetic fields being thrust outwards at speeds much greater than the
solar wind speed, (iii) an electron heat flux drop out occurring within
minutes of the shock indicating a topological change resulting from
disconnection from the solar surface and (iv) a very cold 6 keV proton
beam resulting from reconnection and an associated monochromatic wave.
We expect that, given observations of enough magnetic clouds, WIND and
other spacecraft will see signatures similar to the ones reported here
indicating reconnection. However, these observations require the
spacecraft to be fortuitously positioned to observe the passing shock
and other signatures and will therefore be associated with only a small
fraction of magnetic clouds. Consistent with this, a few other magnetic
clouds observed by WIND have been observed to possess internal shock
waves.