FOUR-DIMENSIONAL TRANSPORT OF GALACTIC COSMIC RAYS IN THE OUTER HELIOSPHERE AND HELIOSHEATH

Journal Article · Mon Aug 10 00:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/701/1/642; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21313668

Florinski, V

2008 marked the beginning of sunspot cycle 24 in the inner heliosphere. Intensities of galactic hydrogen and helium measured by the Voyagers in 2008 were the highest ever recorded and believed to be approaching the interstellar values. We investigate transport of galactic cosmic ray (GCR) protons in the three-dimensional, asymmetric heliosphere, including the inner heliosheath region, by tracking stochastic phase-space trajectories of Parker equation under steady plasma background conditions. The latter is calculated from a three-dimensional MHD model of the global heliosphere that takes into account the effect of neutral hydrogen atoms. The model is applied to quiet solar wind (SW) conditions appropriate for the 2008-2009 solar minimum. Model-derived cosmic-ray spectra and radial gradients are reviewed in the context of Voyager observations in the heliosheath. It is shown that the heliosheath is an important modulation barrier for lower energy ions. Radial cosmic-ray gradients in the heliosheath are expected to be small in the directions of the Voyagers (1.5%-1.8% per AU at 180 MeV). In our model the termination shock does not accelerate GCR ions very efficiently, and their intensities in the heliosheath never exceed interstellar values. Analysis of cosmic-ray residence times in different parts in the heliosphere shows that, prior to their detection, ions spend 3-6 times longer transiting the heliosheath and the heliotail than they spend in the supersonic SW.

• OSTI ID: 21313668
• Journal Information: Astrophysical Journal, Vol. 701, Issue 1; Other Information: DOI: 10.1088/0004-637X/701/1/642; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASYMMETRY
COSMIC RADIATION
EQUATIONS
FOUR-DIMENSIONAL CALCULATIONS
HELIOSPHERE
HELIUM
HYDROGEN
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MEV RANGE 100-1000
PROTONS
SOLAR WIND
STOCHASTIC PROCESSES
SUNSPOTS
THREE-DIMENSIONAL CALCULATIONS