Parker Solar Probe
Parker Solar Probe’s 19th encounter with the Sun serendipitously occurred just over a week before the April 8th eclipse (perihelion was at 03/30/2024 0200UT). At perihelion, Parker reached 11.4Rs. The movies above show our prediction for what the Parker WISPR-I instrument would have seen during the encounter. On the left is the actual spacecraft trajectory. The green line marks 20 Rs (the simulation’s outer boundary is 30 Rs) and the inner-most white circle is the solar surface. On the right is a unique perspective: What would WISPR-I see if it could sit at perihelion, at a fixed Carrington longitude? In this case, we can observe the time-dependent wind flow past. With these types of visualisations, we hope to be able to separate spatial and temporal variability in the structures we see with WISPR.
During this interval, we also made daily predictions of the locations of the source regions of the plasma that Parker likely encountered. The figure on the left below shows AIA observations (from our CHMAP Database Browser), together with the location of the computed coronal holes from the Eclipse model (black curve) and the location of the heliospheric current sheet (red curve). The trajectory of Parker is shown by the looping black line, with asterisks marking each day. The source region every fourth hour is shown by the straight lines coloured according which model solution was used (PFSS, MHD/CORHEL, or MHD/Eclipse). These maps provide direct feedback about the accuracy of the model solutions, and, once the data from Parker is returned, should allow us to better constrain the solutions.
We also used our standard global thermodynamic MHD model as well as the new time-dependent model to predict the in-situ plasma and magnetic signatures that Parker would likely see. This is shown in the lower-right figure. Of particular note is the significant difference between the new data-assimilative prediction (MHD/Eclipse) and the standard model (CORHEL). It will be exciting to try to understand how these differences arise over the next few months and validate the model results with the measurements when they are available.
During the total solar eclipse, Parker’s nominal connectivity will be behind the limb. However, for the spacecraft has already passed over the solar wind sources that will be on the West limb plane of the sky during the eclipse. Based on predictions by the Parker foot-point mapping team, this may be the equatorial coronal hole that was visible near disk centre at perihelion and which we believe provided much of the solar wind that Parker would have measured. Intriguingly, if a CME launches from the west limb just prior to the 8th, not only could we see it during the eclipse, but Parker (and Solar Orbiter) would likely encounter it too.
