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Title: VOYAGER 1 NEAR THE HELIOPAUSE

Abstract

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. 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. 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 againmore » before it finally leaves the heliosphere.« less

Authors:
Publication Date:
OSTI Identifier:
22363945
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 783; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTRIBUTION FUNCTIONS; HELIOSPHERE; HELMHOLTZ INSTABILITY; MAGNETIC FIELDS; PLASMA DENSITY; RAYLEIGH-TAYLOR INSTABILITY; SOLAR CYCLE; SOLAR WIND; STEADY-STATE CONDITIONS; SUN; VOYAGER SPACE PROBES

Citation Formats

Borovikov, S. N., and Pogorelov, N. V., E-mail: nikolai.pogorelov@uah.edu. VOYAGER 1 NEAR THE HELIOPAUSE. United States: N. p., 2014. Web. doi:10.1088/2041-8205/783/1/L16.
Borovikov, S. N., & Pogorelov, N. V., E-mail: nikolai.pogorelov@uah.edu. VOYAGER 1 NEAR THE HELIOPAUSE. United States. https://doi.org/10.1088/2041-8205/783/1/L16
Borovikov, S. N., and Pogorelov, N. V., E-mail: nikolai.pogorelov@uah.edu. Sat . "VOYAGER 1 NEAR THE HELIOPAUSE". United States. https://doi.org/10.1088/2041-8205/783/1/L16.
@article{osti_22363945,
title = {VOYAGER 1 NEAR THE HELIOPAUSE},
author = {Borovikov, S. N. and Pogorelov, N. V., E-mail: nikolai.pogorelov@uah.edu},
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. 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. 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},
url = {https://www.osti.gov/biblio/22363945}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 783,
place = {United States},
year = {2014},
month = {3}
}

Works referencing / citing this record:

Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields
journal, April 2017


Magnetic field and particle measurements made by Voyager 2 at and near the heliopause
journal, November 2019


An Exact Analytical Solution for the Interstellar Magnetic Field in the Vicinity of the Heliosphere
journal, June 2015


Three-Dimensional Kinetic-Mhd Model of the Global Heliosphere with the Heliopause-Surface Fitting
journal, October 2015


WHY ARE THE MAGNETIC FIELD DIRECTIONS MEASURED BY VOYAGER 1 ON BOTH SIDES OF THE HELIOPAUSE SO SIMILAR?
journal, June 2014


Electron Thermal Conduction as a Possible Physical Mechanism to make the Inner Heliosheath Thinner
journal, October 2014


The Heliotail
journal, October 2015


On the nature of the magnetic Rayleigh–Taylor instability in astrophysical plasma: the case of uniform magnetic field strength
journal, July 2016


The IBEX Ribbon and the Thickness of the Inner Heliosheath
journal, July 2018


Magnetic Turbulence Spectra and Intermittency in the Heliosheath and in the Local Interstellar Medium
journal, February 2019


Compressible and Incompressible Magnetic Turbulence Observed in the Very Local Interstellar Medium by Voyager 1
journal, December 2019


LOCAL INTERSTELLAR MAGNETIC FIELD DETERMINED FROM THE INTERSTELLAR BOUNDARY EXPLORER RIBBON
journal, February 2016