A Magnetic Pressure Front Upstream of the Heliopause and the Heliosheath Magnetic Fields and Plasma, Observed during 2017

Voyager 1 (V1), moving in the interstellar magnetic field, observed an increase in the daily averages of B beginning on day 346, 2016, rising to a local maximum on day 382, and declining nearly monotonically for the most part until day 720, measured from 2016.0. A pressure front was observed during...

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Bibliographic Details
Published in:The Astrophysical journal 2019-05, Vol.877 (1), p.31
Main Authors: Burlaga, L. F., Ness, N. F., Berdichevsky, D. B., Jian, L. K., Park, J., Mostafavi, P., Richardson, J. D.
Format: Article
Language:English
Subjects:
Astrophysics
Cosmic ray intensities
Cosmic rays
Heliopause
Heliosphere
Interstellar magnetic fields
ISM: magnetic fields
Magnetic fields
Magnetic flux
Magnetic reconnection
Normal distribution
Nucleons
Polarity
Sun: heliosphere
Sun: magnetic fields
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Summary:Voyager 1 (V1), moving in the interstellar magnetic field, observed an increase in the daily averages of B beginning on day 346, 2016, rising to a local maximum on day 382, and declining nearly monotonically for the most part until day 720, measured from 2016.0. A pressure front was observed during a 35-day interval beginning on day 346, 2016. The pressure front observed by V1 was not a shock, although one might expect it to evolve into a shock. Voyager 2 (V2) observed the distant heliosheath during 2017. The average B in the heliosheath was relatively high, 0.130 nT. The distribution of azimuthal angles had two nearly equal maxima at approximately 90° and 180°. An unusual transition of the BT component from a large "away" sector to a large "toward" sector occurred during 2017 from day 101 to day 239. Abrupt but small changes in magnetic polarity occurred between day 146 and day 239, when the average BT component of B was close to zero. Changes in the >70 MeV nucleon−1 cosmic-ray intensity were qualitatively related to the B(t) profile described by the CR-B relationship. There was no net decrease in magnetic flux at V2 in the heliosheath during 2017 that might be attributed to ongoing magnetic reconnection in the heliosheath. Small-scale increments in B can be described by a q-Gaussian distribution with q = 1.64 0.02 for hourly averages of B and q = 1.54 0.08 for daily averages of B.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab16f1