Can IBEX identify variations in the galactic environment of the sun using energetic neutral atoms?

Priscilla C. Frisch, Jacob Heerikhuisen, Nikolai V. Pogorelov, Bob DeMajistre, Geoffrey B. Crew, Herbert O. Funsten, Paul Janzen, David J. McComas, Eberhard Moebius, Hans Reinhard Mueller, Daniel Brett Reisenfeld, Nathan A. Schwadron, Jonathan D. Slavin, Gary Paul Zank

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


The Interstellar Boundary Explorer (IBEX) spacecraft is providing the first all-sky maps of the energetic neutral atoms (ENAs) produced by charge exchange between interstellar neutral Ho atoms and heliospheric solar wind and pickup ions in the heliosphere boundary regions. The "edge" of the interstellar cloud presently surrounding the heliosphere extends less than 0.1 pc in the upwind direction, terminating at an unknown distance, indicating that the outer boundary conditions of the heliosphere could change during the lifetime of the IBEX satellite. Using reasonable values for future outer heliosphere boundary conditions, ENA fluxes are predicted for one possible source of ENAs coming from outside of the heliopause. The ENA-production simulations use threedimensional MHD plasma models of the heliosphere that include a kinetic description of neutrals and a Lorentzian distribution for ions. Based on this ENA-production model, it is then shown that the sensitivities of the IBEX 1.1 keV skymaps are sufficient to detect the variations in ENA fluxes that are expected to accompany the solar transition into the next upwind cloud. Approximately 20% of the IBEX 1.1 keV pixels appear capable of detecting the predicted model differences at the 3σ level, with these pixels concentrated in the Ribbon region. Regardless of the detailed ENA production model, the success of the modeled B · R ∼ 0 directions in reproducing the Ribbon locus, together with our results, indicates that the Ribbon phenomenon traces the variations in the heliosphere distortion caused by the relative pressures of the interstellar magnetic and gaseous components.

Original languageEnglish (US)
Pages (from-to)1984-1992
Number of pages9
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 20 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • ISM: clouds
  • ISM: kinematics and dynamics
  • ISM: magnetic fields
  • ISM: structure
  • Plasmas
  • Sun: heliosphere


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