Princeton Plasma Physics Laboratory (PPPL) PS&T Seminar

ABSTRACT: The recent measurements in-situ by the Voyager spacecrafts, combined with the all-sky images of the heliospheric boundaries by the Interstellar Boundary Explorer (IBEX) mission have transformed radically our knowledge of the boundaries of the heliosphere. Concepts that resisted decades are being revisited due to their puzzling measurements. In particular after the crossing of the termination shock (TS) by V1 and then by V2, one of the first surprises was that both Voyager found no evidence for the acceleration of the anomalous cosmic rays at the TS as expected for approximately 25 years. Another challenge are the energetically particles intensities that are dramatically different at Voyager 1 and 2. All current global models of the heliosphere are based on the assumption that the magnetic field in the heliosheath is laminar. Recently, we proposed that the annihilation of the “sectored” magnetic field within the heliosheath as it is compressed on its approach to the heliopause produces anomalous cosmic rays and also energetic electrons. As a product of the annihilation of the sectored magnetic field, densely packed magnetic islands (which further interact to form magnetic bubbles) are produced. These magnetic islands/bubbles will be convected with ambient flows as the sector region is carried to higher latitudes filling the heliosheath. As a result, the magnetic field in the heliosheath sector region will be disordered. The sector region in the heliosheath is the region where the heliospheric magnetic field reverses direction and is the ideal place to study reconnection of multiple current layers; and the dynamic of multi-islands. We present a three-dimensional MHD simulation with very high numerical resolution that for the first time solved self-consistently the MHD equations including the sector region. We show that due to the high pressure of the interstellar magnetic field a north–south asymmetry develops such that the disordered sectored region fills a large portion of the northern part of the heliosphere with a smaller extension in the southern hemisphere. In this talk, I will review our model as well as the observations that support this scenario indicating that the presence of the heliospheric current sheet, where the magnetic field reconnected might play a crucial role on organizing the heliosheath; affecting both the flows and transport of energetic particles. Any non-PPPL people interested in attending should see this site for more information: http://www.pppl.gov/visiting.cfm .