Physics of the Solar Wind–Local Interstellar Medium Interaction: Role of Magnetic Fields

Energetic neutral atoms (ENAs) are recognized as a powerful tool for remote probing of distant hot space plasmas, in particular the plasmas abundant at the heliospheric boundary where the expanding solar wind meets the surrounding local interstellar medium. We show here for the first time that the heliospheric ENAs originating in the heliospheric sheath between the termination shock and the heliopause and reaching the inner heliosphere also provide an important and heretofore unaccounted source of atomic hydrogen in the Sun's vicinity. These ENAs are a major contributor to the density of interplanetary hydrogen at heliocentric distances <1 AU and could dominate in the downwind (interstellar wind) region under typical solar and interstellar conditions. Mass transport by heliospheric ENAs may become especially important for determining the origin of the pickup ions attributed to the inner source of neutral particles in the Sun's vicinity and for characterization of the three‐dimensional solar wind flow by imaging in extreme ultraviolet.

Heliosphere

Energetic neutral atom

Interplanetary medium

10.1029/2004ja010727

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Citations (14)

Diffusion of solar cosmic rays and the power spectrum of the interplanetary magnetic field

Journal of Geophysical Research Atmospheres (1968)

K. V.S.K. Nathan J. A. Van Allen

Van Allen and Krimigis find that solar electrons diffuse through the interplanetary medium at a rate that is similar to that of protons of the same velocity, despite the disparity by a factor of 2 × 10³ in their respective magnetic rigidities, and they suggest that this fact serves to extend knowledge of the structure of the interplanetary magnetic field to much smaller scale than has been measured by Coleman. This suggestion is developed quantitatively in the framework of Roelof's theory. It is found that the power spectrum of the interplanetary magnetic field varies inversely as the square of the frequency ƒ in the range 2.7 × 10−4 < ƒ < 0.5 cps.

Interplanetary medium

10.1029/ja073i001p00163

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Citations (10)