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Title: THE SOLAR WIND AS A POSSIBLE SOURCE OF FAST TEMPORAL VARIATIONS OF THE HELIOSPHERIC RIBBON

We present a possible source of pickup ions (PUIs) the ribbon observed by the Interstellar Boundary EXplorer (IBEX). We suggest that a gyrating solar wind and PUIs in the ramp and in the near downstream region of the termination shock (TS) could provide a significant source of energetic neutral atoms (ENAs) in the ribbon. A fraction of the solar wind and PUIs are reflected and energized during the first contact with the TS. Some of the solar wind may be reflected propagating toward the Sun but most of the solar wind ions form a gyrating beam-like distribution that persists until it is fully thermalized further downstream. Depending on the strength of the shock, these gyrating distributions can exist for many gyration periods until they are scattered/thermalized due to wave-particle interactions at the TS and downstream in the heliosheath. During this time, ENAs can be produced by charge exchange of interstellar neutral atoms with the gyrating ions. In order to determine the flux of energetic ions, we estimate the solar wind flux at the TS using pressure estimates inferred from in situ measurements. Assuming an average path length in the radial direction of the order of a few AU before themore » distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. With a localized source and such a short integration path, this model would also allow fast time variations of the ENA flux.« less
Authors:
; ; ;  [1] ; ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6]
  1. Space Science Center, University of New Hampshire, Durham, NH (United States)
  2. Southwest Research Institute, San Antonio, TX (United States)
  3. Physikalisches Institut der Universitaet Bern, Bern (Switzerland)
  4. Physics Department and Center of Space Plasma and Aeronomic Research, The University of Alabama, Huntsville, AL (United States)
  5. Department of Physics and Astronomy, University of Montana, Missoula, MT (United States)
  6. Center of Space Science and Exploration, Los Alamos National Laboratory, Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
22270793
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; ATOMS; CHARGE EXCHANGE; INTERSTELLAR SPACE; MAGNETIC FIELDS; SHOCK WAVES; SOLAR WIND; SUN; TAIL IONS; VARIATIONS