Predicted timing for the turn‐on of radiation in the outer heliosphere due to the Bastille Day shock

The propagation of the July 14, 2000 (Bastille Day), shock complex is modeled throughout the heliosphere, including its interaction with the solar wind termination shock and subsequent propagation into the inner heliosheath. The model includes pickup ions and the ionization cavity explicitly. The Bastille Day shock is used (1) to predict the time when the Voyager spacecraft can expect to observe 2‐ to 3‐kHz radiation and (2) to place constraints on the distance to the heliopause in the upwind or nose direction. On the basis of the most widely accepted model for the generation of the 2‐ to 3‐kHz radiation, we predict that the Bastille Day shock, were it to produce observable radiation in the outer heliosheath, would turn on in mid‐October 2001. The distance to the heliopause at the nose is then estimated to be < 120–130 AU, and the distance to the termination shock is estimated to be <90 AU. A further conclusion is that transmitted interplanetary shocks are very weak when they enter the outer heliosheath, the putative site at which interplanetary shocks radiate, thus requiring that the interstellar plasma in this region be primed with a preexisting energized electron population.