2019 Physics/Theoretical Colloquium
 
Thursday, August 29th , 2019
3:45 – 4:45 p.m.
Rosen Auditorium (TA-53, Bldg. 001)
 
 
Refreshments at 3:15pm
 
Speaker:   Dr. Daniel Reisenfeld
ISR-1: Space Sciences and Applications 
 
“Exploring the Interstellar Boundary with Voyager, IBEX, and IMAP”
Abstract: 
 
The solar wind flows outward from the sun in all directions, inflating a bubble in the local interstellar medium (LISM) called the heliosphere. In 2004 and 2007 the Voyager 1 and 2 spacecraft crossed the heliosphere’s termination shock providing us with the first direct observations of the interaction of the heliosphere with the LISM. Then, the Interstellar Boundary Explorer (IBEX) was launched in 2008, and has since been continuously returning full-sky observations of ion distributions in the interstellar boundary layer, or heliosheath, via the observation of Energetic Neutral Atoms (ENAs) formed in that region.  Measurements from the LANL-led IBEX-Hi instrument have shown that the heliosheath is quite dynamic, changing with time in step with the solar cycle.  IBEX-Hi observations have also led to the discovery of a completely unpredicted band of enhanced ENA emission, coined the IBEX Ribbon, that encircles our solar system.
 
The success of IBEX has set the stage for the next-generation heliospheric mission, the Interstellar Mapping and Acceleration Probe (IMAP), which will simultaneously investigate the solar wind/LISM interaction as well as the acceleration of energetic particles throughout the heliosphere.  While seemingly disparate, these two areas of study are intimately coupled because particles accelerated in the inner heliosphere play critical, and so far, only sparsely observed roles in heliosheath interactions. Selected by NASA in June 2018, IMAP is slated to launch in 2024. Two of IMAP’s suite of 10 instruments will be led by LANL: IMAP-Hi which will detect heliospheric ENAs between 0.5 and 15 keV, and SWE, which will measure in situ solar wind electrons.  I will survey our current knowledge of the heliosphere/LISM interaction as discovered by Voyager and IBEX, and how IMAP plans to deepen our understanding.