LENAs in the Magnetosphere

1
LENAs in the Magnetosphere

• T. E. Moore1, M. R. Collier1, J. L. Burch2, D. J.
  Chornay1,3, B. El Marji1,3, M-C. Fok1, S. A.
  Fuselier4, A. G. Ghielmetti4, B. L. Giles1, D. C.
  Hamilton3, F. A. Herrero1, J. W. Keller1, K. W.
  Ogilvie1, B. L. Peko5, J. M. Quinn6, T. M.
  Stephen5, G. R. Wilson7, P. Wurz8
• 1. NASA Goddard Space Flight Center, Greenbelt,
  MD 20771 USA
• 2. Southwest Research Institute, San Antonio, TX
  78228-510 USA
• 3. University of Maryland, College Park, MD 20742
  USA
• 4. Lockheed Martin Adv. Tech. Center, Palo Alto,
  CA 94304 USA
• 5. University of Denver, Dept. of Physics,
  Denver, CO 80208 USA
• 6. University of New Hampshire, Inst. for EOS,
  Durham, NH 03824 USA
• 7. Mission Research Corp., 1 Tara Blvd., Nashua,
  NH 03062 USA
• 8. University of Bern, Bern, CH-3012 Switzerland

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LENAs in the magnetosphere
Typical Quiet Day. Sun in FOV
CME Arrival 0915. Sun beyond FOV
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Quiet Day Image Sequence
Typical Quiet Day Sun flux nearing
eclipseby Earth
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8 June CME Event Evolution
Indirect solar flux beyond imager FOV Brightens
x2 at CME Outflow response Snapshot shows burst
exceeds solar flux, briefly
5
8 June LENA temporal development
Burst occurs with 35 min delay relative to CME
shock arrival. Consistent with 35 eV O0 at
source (20 km/s).
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Lack of EUV enhancement
No EUV enhancement observed in association with
6/8 CME.
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Solar LENA flux profile
Strong similarity to ram pressure profile
observed at WIND.
8
8 June CME LENA composition

• LENA known to respond toenergetic H as O
  sputteredfrom conversion surface
• Sun signal at times registers in the O range of
  TOFs

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Apparent Composition Change
Apparent composition change at CME arrival
suggests velocity/energy dependent sputtering
response to neutral atoms.
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Sources of LENA from the solar wind
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Simulation of Magnetosheath LENAs

• Analogous to ring current ENA simulations, using
  an MHD model of the magnetosheath, and looking
  out.
• LOS integration from 8 to 50 RE, excepting
  antisunward direction. Images collapsed in polar
  angle, for IMAGE.
• No true solar LENAs assumed to arrive in solar
  wind at present.

200 eV
4000 eV
Dawn-Dusk Orbit
Dawn-Dusk Orbit
Noon-Midnight Orbit
Noon-Midnight Orbit
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Possibility of Cusp Imaging
LOS r gt 5 Re

• Series of 1keV simulations, oblique orbit.
• LOS integration from increasing Rmin.
• Gradually lose features interpreted as cusp/cleft
  intrusions.
• Remote sensing of cusp and cleft possible with
  sufficient sensitivity.

LOS r gt 7 Re
LOS r gt 8 Re
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Conclusions

• Magnetosphere contains LENAs from the solar wind
• Indirect LENAs from the magnetosheath and cusps.
• Flux 10-4 of solar wind ion flux
• Similar to predicted Gruntman, 94 JGR
• Direct LENAs when in imager FOV.
• Flux somewhat higher (x10) than indirect flux.
• Quantitative interpretation requires additional
  modeling and correlative study (w/ solar EUV,
  solar wind).
• Magnetosphere contains LENAs from the ionosphere
• Apogee fluxes up to 106 s-1cm-2 from the Earth
  sector.
• Energies 30 eV
• Perigee fluxes up to 108 s-1cm-2sr-1
• O energies down to 5eV or lower (ram energy)
• Additional modeling and correlative study is
  needed.