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Title: EVIDENCE FOR A SHOCK IN INTERSTELLAR PLASMA: VOYAGER 1

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{sub e}  = 0.05 cm{sup –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{sup 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,more » 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.« less
Authors:
 [1] ;  [2] ; ;  [3]
  1. NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States)
  2. Institute for Astrophysics and Computational Sciences, Catholic University of America, Washington, DC 20064 (United States)
  3. University of Iowa, Iowa City, IA 52242 (United States)
Publication Date:
OSTI Identifier:
22364142
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 778; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COSMIC ELECTRONS; ELECTRON DENSITY; HELIOSPHERE; INTERSTELLAR SPACE; MAGNETIC FIELDS; PLASMA WAVES; SUN; VOYAGER SPACE PROBES