Warmer Local Interstellar Medium: Resolving the Ulysses-Ibex Enigma and the Promise of IMAP

Tuesday, 16 December 2014: 8:30 AM
David J McComas1,2, Maciej Bzowski3, Priscilla C Frisch4, Stephen Fuselier1,2, Marzena A. Kubiak3, Harald Kucharek5, Trevor Leonard5, Eberhard Moebius5, Nathan Schwadron5, Justyna M Sokol3, Pawel Swaczyna3 and Manfred Witte6, (1)Southwest Res Inst, San Antonio, TX, United States, (2)University of Texas at San Antonio, Department of Physics & Astronomy, San Antonio, TX, United States, (3)Space Research Center Polish Academy of Sciences, Warsaw, Poland, (4)University of Chicago, Chicago, IL, United States, (5)Univ New Hampshire, Durham, NH, United States, (6)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
While charged particles from the local interstellar medium (LISM) are convected around our heliosphere with the magnetized LISM flow, the neutral interstellar atoms flow directly into and through the heliosphere. Initial measurements from the Interstellar Boundary Explorer (IBEX) suggested that the heliosphere could be moving more slowly with respect to the interstellar medium than indicated by earlier observations from the Ulysses spacecraft. In this study we refine the range of possible IBEX flow parameters based on the latest measurements and show that both spacecraft’s data could be consistent with a single flow velocity for a much larger interstellar neutral temperature (7000-9000K) than previously found. Combining the IBEX and Ulysses observations suggests that the heliosphere is currently in a substantially warmer region of the interstellar medium than previously thought. This study examines this possible resolution of the prior apparent disconnect between these observations. We further examine the incredible improvement in interstellar observations – and our understanding of the local interstellar medium – that the envisioned Interstellar Mapping and Acceleration Probe (IMAP) will provide.