Predicted Voyager observations of the Bastille Day 2000 coronal mass ejection

Abstract

The most powerful solar flare detected so far this solar cycle occurred on July 14, 2000. At approximately the same time, the Large‐Angle Spectrometric Coronograph instruments on Solar and Heliospheric Observatory observed a bright, fast, halo coronal mass ejection (CME) headed earthward at ∼1300 to 1800 km s−1. The ejecta reached Earth on July 15 and produced a very significant magnetic storm and aurora. At 1 AU the IMP 8 spacecraft recorded a strong forward shock with a speed increase from ∼600 to over 1000 km s−1. In this study, we use numerical models which include the mutual influence of the interstellar and solar wind plasma and the interstellar neutral hydrogen to study the propagation of the strong CME shock to the locations of Voyagers 1 and 2, the termination shock, and the heliopause. We predict that Voyager 2 will see a relatively strong forward shock with a speed jump of ∼65 km s−1 and a compression ratio of ∼1.9 in January 2001. Voyager 1 will see a similar shock in March 2001 with a speed jump of ∼60 km s−1 and a compression ratio of ∼1.8. This strong shock will continue its journey through the heliosphere and is expected to arrive at the termination shock and heliopause in March and December 2001, respectively. The impingement of this strong interplanetary disturbance on the denser plasma past the heliopause could trigger the next 2–3 kHz heliospheric radio emission event, which would then occur at the end of 2001.