June 15, 2018, 1:00 pm - 2:00 pm

June 15, 2018, 1:00 pm - 2:00 pm, Heliophysics Director's Seminar, Hosted by the Heliospheric Physics Laboratory (672)

Interstellar Ion Flow surrounding the Heliopause Estimated by IBEX-Lo Observations

Jeewoo Park (NPP/672)

Relative motion of the Sun with respect to the local interstellar medium results in entering of neutral atoms existing in the outer heliosheath into the inner heliosphere. These neutral populations include the unperturbed interstellar neutral (ISN) atoms, which is called the primary ISNs, and the secondary ISN populations created by the charge-exchange reactions between the interstellar ions and the ambient neutral atoms in the outer heliosheath. Since resonant charge-exchange reactions operate practically without momentum exchange between the collision partners, the new populations of neutralized interstellar ions inherit the local physical state of the ambient plasma. Therefore, the measurement of the secondary ISNs is an essential diagonal tool to understand the global structure of our heliosphere. Since 2009, the IBEX-Lo neutral-atom detector on board the Interstellar Boundary Explorer (IBEX) have observed the neutral atoms entering into the heliosphere from the outer heliosheath. The IBEX-Lo measurements reveal two prominent features in the directional distribution of the inflowing neutral atoms: the core emission and the tail-like emission extended toward lower ecliptic longitude and higher latitude. The secondary ISN populations most likely contribute the extended tail-like emission. This talk will present the directional distribution of the extended tail-like emission at Earth?s orbit and describe a methodology to analyze this distribution with a simple analytical model.

New IBEX results and prospects for the future

Eric Christian (GSFC)

There has been considerable progress in solving the primary mystery discovered by IBEX, the origin of the ribbon of ENAs at the edge of the heliosphere. Although there is a theory for the origin that is considered a front-runner by many in the community, the case is definitely not settled. In addition, there are still many new interesting results coming out of IBEX. This talk will briefly cover a number of them. Adding to the excitement, NASA has just selected the Interstellar Mapping and Acceleration Probe, IMAP, as the next Solar Terrestrial Probes mission, with a launch NLT 2024. IMAP will have improved heliospheric ENA measurements as compared to IBEX. The science and capabilities of the new IMAP mission will also be presented.