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Database: Current Contents(tm) from ISI
Copyright 1992, 1995 Institute for Scientific Information, all rights reserved.
Author: HALL-D-T*; SHEMANSKY-D-E; JUDGE-D-L; GANGOPADHYAY-P;
GRUNTMAN-M-A
Title: HELIOSPHERIC HYDROGEN BEYOND 15 AU - EVIDENCE FOR A
TERMINATION SHOCK
Source: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, vol. 98,
issue A9, (SEP 1, 1993) : pp. 15185-15192.
Abstract: The Voyager and Pioneer 10 spacecraft are moving upstream
and downstream into the local interstellar flow, monitoring H
Lyman alpha radiation resonantly scattered from heliospheric
hydrogen. Voyager Cruise Maneuver observations obtained between
15 and 35 AU reveal that H Lyman alpha intensities in the
upstream direction fall as r-0.75+/-0.05. Beyond 15 AU
downstream, Pioneer 10 intensities fall as r-1.07+/-0.1. These
trends cannot be simultaneously reproduced using a hot H
distribution model that does not include termination shock
structure. Radiative transfer calculations using the hot H
model predict that upstream intensities should fall more rapidly
as a function of heliocentric distance than downstream
intensities, precisely opposite to the observed trends. The
Voyager H Lyman alpha intensities also show a distinctive trend
to decrease less rapidly with increasing heliocentric distance.
Between 15 and 20 AU, Voyager intensities fall as r-1, whereas
between 30 and 35 AU they fall as r-0.35. This flattening trend
implies that the upstream H density is increasing rapidly with
heliocentric distance beyond almost-equal-to 25 AU. A simple
analysis suggests that the density distribution changes from
nearly uniform between 15 and 20 AU, to r0.65 dependence between
30 and 35 AU. This steepening trend is significant because
similar H density gradients are predicted in models which
include the effects of the termination shock. Taken together,
the Voyager and Pioneer 10 H Lyman alpha observations beyond 15
AU imply the existence of a solar wind termination shock,
suggesting that it lies between 70 and 105 AU in the upstream
direction.
Authors Abstract: N
English Abstract: Y
Language: eng
Pub. Type: ARTICLE
References: 56
ISSN: 0148-0227
ISI Order #: LW353 (For ordering reprints from ISI) |
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