Open AccessEnergetic neutral atom imaging of the heliospheric boundary region
Author(s) -
Gruntman Mike,
Roelof Edmond C.,
Mitchell Donald G.,
Fahr Hans J.,
Funsten Herbert O.,
McComas David J.
Publication year - 2001
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000ja000328
Subject(s) - heliosphere , energetic neutral atom , physics , solar wind , interstellar medium , interplanetary medium , proton , bow shock (aerodynamics) , astrophysics , plasma , interplanetary spaceflight , shock wave , nuclear physics , galaxy , thermodynamics
Energetic neutral atom (ENA) imaging is a powerful technique, which can remotely probe the properties of distant hot plasmas. Hot plasmas are abundant at the heliospheric boundary, the region where the expanding solar wind meets the surrounding local interstellar cloud. Here we present a new concept for imaging this boundary in ENA fluxes. Heliospheric ENAs are born from charge exchange between energetic protons and the background interstellar atomic hydrogen gas. The technique is ideal for studying the asymmetric three‐dimensional heliospheric interface region remotely, from 1 AU. We show that ENA imaging in the 0.2–6 keV energy range will establish the nature of the termination shock and properties of hot proton populations in the heliosheath. We also examine how the evolution of pickup proton populations at and beyond the shock can be explored. Global heliosphere ENA images will distinguish among the competing models of the interaction between the Sun and the local interstellar medium, and they will reveal the physics of important processes in the interface region. Heliospheric ENA fluxes are exceptionally weak, which makes imaging implementation difficult. Nonetheless, we show how single‐pixel ENA sensors can image the heliosphere from a spinning spacecraft on a typical mission near 1 AU. The required instrumentation is briefly discussed.