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González-Esparza & Bravo 1998
González-Esparza, J.A. and Bravo, S. (1998). Two spacecraft observations of transient shocks and ejecta in the interplanetary medium. Journal of Geophysical Research 103: doi: 10.1029/98JA02824. issn: 0148-0227.

We compare Ulysses observations of 22 forward transient shocks (FTSs) and 11 ejecta during the first 19 months of its mission, with observations near Earth by IMP, in order to infer some properties of the propagation of these transient events in the interplanetary medium. We found that 13 of the 22 FTSs detected by Ulysses were also detected by IMP. The average of the mean radial transit speed of these 13 FTSs from 1 AU to Ulysses was about 504 km/s, which is slower than previous reports of transit speeds within 1 AU, suggesting shock deceleration beyond 1 AU. We found that whenever (in all cases) the two spacecraft detected the same FTS, the spacecraft were located within the same magnetic sector. During the period of the study we found 9 FTSs detected only by Ulysses and 10 FTSs detected only by IMP. For 16 of these shocks the two spacecraft were located within different magnetic sectors. The results suggest that magnetic sectors play a role in the propagation of transient shocks. Of the 11 ejecta detected by Ulysses, 7 of them also passed by IMP. The average of the mean radial transit speed of the 7 ejecta was about 407 km/s. In every case the radial width of the ejecta was larger at Ulysses than at IMP, showing a radial expansion with heliocentric distance. In the four events that we could estimate the shock--ejecta radial separation at 1 AU and Ulysses, we found that this radial distance was larger at Ulysses. ¿ 1998 American Geophysical Union

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Abstract

Keywords
Interplanetary Physics
Journal
Journal of Geophysical Research
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American Geophysical Union
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