PICK-UP IONS IN THE OUTER HELIOSHEATH: A POSSIBLE MECHANISM FOR THE INTERSTELLAR BOUNDARY EXplorer RIBBON

Journal Article · Sun Jan 10 04:00:00 EST 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/708/2/L126; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301252

Heerikhuisen, J; Pogorelov, N V; Zank, G P ^[1]; Crew, G B; Schwadron, N A ^[2]; Frisch, P C ^[3]; Funsten, H O ^[4]; Janzen, P H; Reisenfeld, D B ^[5]

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1. Department of Physics and Center for Space Physics and Aeronomic Research, University of Alabama, Huntsville, AL 35899 (United States)
2. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
3. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
4. Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
5. University of Montana, Missoula, MT 59812 (United States)

First data from NASA's Interstellar Boundary EXplorer (IBEX) mission show a striking 'ribbon' feature of enhanced energetic neutral atom (ENA) emission. The enhancement in flux is between 2 and 3 times greater than adjacent regions of the sky. Yet the spectral index of ENAs appears to be the same both inside and outside the ribbon. While the ribbon itself was not predicted by any models of the heliospheric interface, its geometry appears to be related to the predicted interstellar magnetic field (ISMF) outside the heliopause (HP). In this Letter, we examine a process of ENA emission from the outer heliosheath, based on a source population of non-isotropic pick-up ions that themselves originate as ENAs from inside the HP. We find that our simplistic approach yields a ribbon of enhanced ENA fluxes as viewed from the inner heliosphere with a spatial location and ENA flux similar to the IBEX measurements, with the provision that the ions retain a partial shell distribution long enough for the ions to be neutralized. As a corollary, our idealized simulation of this mechanism suggests that ISMF is likely oriented close to the center of the observed ribbon.

• OSTI ID: 21301252
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 708; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
EMISSION
HELIOSPHERE
INTERSTELLAR MAGNETIC FIELDS
SIMULATION
SOLAR WIND