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Title: The solar wind as a possible source of fast temporal variations of the heliospheric ribbon

Here 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 beforemore » the distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. In conclusion, 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] ;  [4] ;  [1] ;  [1] ;  [5] ;  [6] ;  [1] ;  [2]
  1. Univ. of New Hampshire, Durham, NH (United States). Space Science Center
  2. Southwest Research Inst. (SwRI), San Antonio, TX (United States); Univ. of Texas, San Antonio, TX (United States). Dept. of Physics
  3. Univ. Bern, Bern (Switzerland). Physical Inst.
  4. Univ. of Alabama in Huntsville, AL (United States). Center of Space Plasma and Aeronomic Research (CSPAR), Dept. of Physics
  5. Univ. of Montana, Missoula, MT (United States). Dept. of Physics and Astronomy
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center of Space Science and Exploration
Publication Date:
Grant/Contract Number:
SC0008334; NNX09AG62G
Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 776; Journal Issue: 2; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Research Org:
Univ. of Alabama, Huntsville, AL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; ISM: atoms; ISM: magnetic fields; shock waves; solar wind
OSTI Identifier:
1326049

Kucharek, H., Fuselier, S. A., Wurz, P., Pogorelov, N., Borovikov, S., Lee, M. A., Moebius, E., Reisenfeld, D., Funsten, H., Schwadron, N., and McComas, D.. The solar wind as a possible source of fast temporal variations of the heliospheric ribbon. United States: N. p., Web. doi:10.1088/0004-637X/776/2/109.
Kucharek, H., Fuselier, S. A., Wurz, P., Pogorelov, N., Borovikov, S., Lee, M. A., Moebius, E., Reisenfeld, D., Funsten, H., Schwadron, N., & McComas, D.. The solar wind as a possible source of fast temporal variations of the heliospheric ribbon. United States. doi:10.1088/0004-637X/776/2/109.
Kucharek, H., Fuselier, S. A., Wurz, P., Pogorelov, N., Borovikov, S., Lee, M. A., Moebius, E., Reisenfeld, D., Funsten, H., Schwadron, N., and McComas, D.. 2013. "The solar wind as a possible source of fast temporal variations of the heliospheric ribbon". United States. doi:10.1088/0004-637X/776/2/109. https://www.osti.gov/servlets/purl/1326049.
@article{osti_1326049,
title = {The solar wind as a possible source of fast temporal variations of the heliospheric ribbon},
author = {Kucharek, H. and Fuselier, S. A. and Wurz, P. and Pogorelov, N. and Borovikov, S. and Lee, M. A. and Moebius, E. and Reisenfeld, D. and Funsten, H. and Schwadron, N. and McComas, D.},
abstractNote = {Here 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 the distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. In conclusion, with a localized source and such a short integration path, this model would also allow fast time variations of the ENA flux.},
doi = {10.1088/0004-637X/776/2/109},
journal = {Astrophysical Journal},
number = 2,
volume = 776,
place = {United States},
year = {2013},
month = {10}
}