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Title: Voyager 1 Near the heliopause

Recent observations from the Voyager 1 spacecraft show that it is sampling the local interstellar medium (LISM). This is quite surprising because no realistic, steady-state model of the solar wind (SW) interaction with the LISM gives an inner heliosheath width as narrow as ~30 AU. This includes models that assume a strong redistribution of the ion energy to the tails in the pickup ion distribution function. We show that the heliopause (HP), which separates the SW from the LISM, is not a smooth tangential discontinuity, but rather a surface subject to Rayleigh-Taylor-type instabilities which can result in LISM material penetration deep inside the SW. We also show that the HP flanks are always subject to a Kelvin-Helmholtz instability. The instabilities are considerably suppressed near the HP nose by the heliospheric magnetic field in steady-state models, but reveal themselves in the presence of solar cycle effects. Here we argue that Voyager 1 may be in one such instability region and is therefore observing plasma densities much higher than those in the pristine SW. Lastly, these results may explain the early penetration of Voyager 1 into the LISM. They also show that there is a possibility that the spacecraft may start samplingmore » the SW again before it finally leaves the heliosphere.« less
Authors:
 [1] ;  [2]
  1. Univ. of Alabama in Huntsville, AL (United States). Center for Space Physics and Aeronomic Research (CSPAR)
  2. Univ. of Alabama in Huntsville, AL (United States). Dept. of Space Sciences
Publication Date:
Grant/Contract Number:
SC0008334; NNX10AE46G; NNX10AC17G; NNX12AB30G; OCI-1144120
Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 783; Journal Issue: 1; Journal ID: ISSN 2041-8205
Publisher:
Institute of Physics (IOP)
Research Org:
Univ. of Alabama, Huntsville, AL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; ISM: kinematics and dynamics; ISM: magnetic fields; solar wind; Sun: heliosphere
OSTI Identifier:
1326044

Borovikov, S. N., and Pogorelov, N. V.. Voyager 1 Near the heliopause. United States: N. p., Web. doi:10.1088/2041-8205/783/1/L16.
Borovikov, S. N., & Pogorelov, N. V.. Voyager 1 Near the heliopause. United States. doi:10.1088/2041-8205/783/1/L16.
Borovikov, S. N., and Pogorelov, N. V.. 2014. "Voyager 1 Near the heliopause". United States. doi:10.1088/2041-8205/783/1/L16. https://www.osti.gov/servlets/purl/1326044.
@article{osti_1326044,
title = {Voyager 1 Near the heliopause},
author = {Borovikov, S. N. and Pogorelov, N. V.},
abstractNote = {Recent observations from the Voyager 1 spacecraft show that it is sampling the local interstellar medium (LISM). This is quite surprising because no realistic, steady-state model of the solar wind (SW) interaction with the LISM gives an inner heliosheath width as narrow as ~30 AU. This includes models that assume a strong redistribution of the ion energy to the tails in the pickup ion distribution function. We show that the heliopause (HP), which separates the SW from the LISM, is not a smooth tangential discontinuity, but rather a surface subject to Rayleigh-Taylor-type instabilities which can result in LISM material penetration deep inside the SW. We also show that the HP flanks are always subject to a Kelvin-Helmholtz instability. The instabilities are considerably suppressed near the HP nose by the heliospheric magnetic field in steady-state models, but reveal themselves in the presence of solar cycle effects. Here we argue that Voyager 1 may be in one such instability region and is therefore observing plasma densities much higher than those in the pristine SW. Lastly, these results may explain the early penetration of Voyager 1 into the LISM. They also show that there is a possibility that the spacecraft may start sampling the SW again before it finally leaves the heliosphere.},
doi = {10.1088/2041-8205/783/1/L16},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 783,
place = {United States},
year = {2014},
month = {2}
}