Exploring the global shock scenario at multiple points between sun and earth: The solar transients launched on January 1 and September 23, 1978
We revisit the transient interplanetary events of January 1 and September 23, 1978. Using in-situ and remote sensing observations at locations widely separated in longitudes and distances from the Sun, we infer that in both cases the overall shock surface had a very fast “nose” region with speeds >900 and >1500 km−1 in the January and September events, respectively, and much slower flank speeds (∼600 km−1 or less), suggesting a shock surface with a strong speed gradient with heliospheric longitude. The shock-nose regions are thus likely efficient acceleration sites of MeV ions, even at 1 AU from the Sun. Our 3D magnetohydrodynamics modeling suggests that a 24° × 24° localized disturbance at 18 solar radii injecting momentum 100 times the background solar wind input over 1 h can produce a disturbance in semi-quantitative agreement with the observed shock arrival time, plasma density and velocity time series in the January 1978 event.
Advances in Space Research
Digital Object Identifier (DOI)
Berdichevsky, D. B.; Reames, D. V.; Wu, C. -C.; Schwenn, R.; Lepping, R. P.; MacDowall, R. J.; Farrugia, C. J.; Bougeret, J. -L.; Ng, C.; Lazarus, A. J. (2009). Exploring the global shock scenario at multiple points between sun and earth: The solar transients launched on January 1 and September 23, 1978, ADVANCES IN SPACE RESEARCH. Vol. 43, No. 1, 113-119. DOI: 10.1016/j.asr.2008.03.026