dorsal/arxiv
View SchemaParticle Propagation Upstream of CIR Shocks
| Authors | M. Savopulos, J. J. Quenby, M. K. Joshi, M. Fraenz |
|---|---|
| Categories | |
| ArXiv ID | physics/0011064 |
| URL | https://arxiv.org/abs/physics/0011064 |
Abstract
The first high solar latitude pass of the Ulysses spacecraft revealed the presence of MeV particle increases up to latitudes above 60 degrees, well outside the CIR belt but associated in time with the regular passage of these plasma interfaces at more equatorial latitudes. The particle increases have been explained variously as due to diffusion from a field line connection with a CIR at a greater distance, perpendicular diffusion in latitude, propagation from the inner Corona or an acceleration process on a connecting field line. Numerical solutions to the 1-D propagation equation upstream of a CIR shock for reasonable diffusion mean free paths are shown here to limit the source of the increases to within about 2 AU of the CIR's, asssuming the CIR's either trap or accelerate energetic particles and they diffuse from the nearby CIR interface. The problem of allowing propagation from the CIR's is eased if the CIRs are located according to the predictions for the current sheet with a solar source surface at $2.5 R_{s}$, rather than at $3.25 R_{s}$. Energetic electron observations showing delays with respect to the CIR-associated ions suggest possibly an acceleration in the inner corona, rather than in the CIR-associated shock. A more likely explanation, however, is the ability of electrons to take a longer a longer route, from beyond the point of observation, than for that of the ions and yet arrive within a few days of CIR closest approach time.
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"abstract": "The first high solar latitude pass of the Ulysses spacecraft revealed the\npresence of MeV particle increases up to latitudes above 60 degrees, well\noutside the CIR belt but associated in time with the regular passage of these\nplasma interfaces at more equatorial latitudes. The particle increases have\nbeen explained variously as due to diffusion from a field line connection with\na CIR at a greater distance, perpendicular diffusion in latitude, propagation\nfrom the inner Corona or an acceleration process on a connecting field line.\nNumerical solutions to the 1-D propagation equation upstream of a CIR shock for\nreasonable diffusion mean free paths are shown here to limit the source of the\nincreases to within about 2 AU of the CIR\u0027s, asssuming the CIR\u0027s either trap or\naccelerate energetic particles and they diffuse from the nearby CIR interface.\nThe problem of allowing propagation from the CIR\u0027s is eased if the CIRs are\nlocated according to the predictions for the current sheet with a solar source\nsurface at $2.5 R_{s}$, rather than at $3.25 R_{s}$. Energetic electron\nobservations showing delays with respect to the CIR-associated ions suggest\npossibly an acceleration in the inner corona, rather than in the CIR-associated\nshock. A more likely explanation, however, is the ability of electrons to take\na longer a longer route, from beyond the point of observation, than for that of\nthe ions and yet arrive within a few days of CIR closest approach time.",
"arxiv_id": "physics/0011064",
"authors": [
"M. Savopulos",
"J. J. Quenby",
"M. K. Joshi",
"M. Fraenz"
],
"categories": [
"physics.space-ph"
],
"title": "Particle Propagation Upstream of CIR Shocks",
"url": "https://arxiv.org/abs/physics/0011064"
},
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