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EVIDENCE FOR A SHOCK IN INTERSTELLAR PLASMA: VOYAGER 1
Journal article   Open access   Peer reviewed

EVIDENCE FOR A SHOCK IN INTERSTELLAR PLASMA: VOYAGER 1

L. F. Burlaga, N. F. Ness, D. A. Gurnett and W. S. Kurth
Astrophysical journal. Letters, Vol.778(1), pp.1-5
11/20/2013
DOI: 10.1088/2041-8205/778/1/L3
url
https://doi.org/10.1088/2041-8205/778/1/L3View
Published (Version of record) Open Access

Abstract

Voyager 1 (V1) observed electron plasma oscillations preceding a jump by a factor of 1.4 in the magnetic field intensity B near the end of 2012. The frequency of the electron plasma oscillations gives an electron density n(e) = 0.05 cm(-3), which implies that V1 was immersed in plasma from the interstellar medium. The last day on which plasma oscillations were observed is day 332, 2012, and the jump in the B was centered on day 335, 2012 after a data gap in the wave data. The close association between the electron plasma oscillations and the jump in B suggests a causal connection, such as that frequently observed between electron plasma oscillations and interplanetary shocks at 1 AU. Based on the observed parameters and the smooth profile of B(t), the jump in B appears to be associated with a weak, subcritical, laminar, low beta, quasi-perpendicular, resistive, collisionless shock. However, the width of the jump is of the order of 10(4) times that expected for such a stationary shock at 1 AU. The large width of the jump in B might be the result of differences between the structure of shocks in the interstellar medium and the plasma near 1 AU. Alternatively, the subcritical resistive shock might have decayed during a few days after producing the plasma waves, leaving a broad profile in B(t) without significantly changing ambient parameters. Another possibility is that the jump in B is a pressure wave.
Physical Sciences Astronomy & Astrophysics Science & Technology

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