A Large Magnetic Hump in the VLISM Observed by Voyager 1 in 2020–2022

Voyager 1 has been moving through the very local interstellar medium (VLISM) for approximately one solar cycle, from 122.58 au on 2012/DOY 238 (August 25) to 158.5 au on 2023.0. Previously, an abrupt increase (“jump”) in the magnetic field strength B and proton density N by a factor of 1.35 and 1.36...

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Bibliographic Details
Published in:The Astrophysical journal 2023-08, Vol.953 (2), p.135
Main Authors: Burlaga, L. F., Pogorelov, N., Jian, L. K., Park, J., Szabo, A., Ness, N. F.
Format: Article
Language:English
Subjects:
Astrophysics
Compression waves
Dynamic pressure
Field strength
Heliopause
Heliosphere
Interstellar magnetic fields
Interstellar medium
Local interstellar medium
Longitudinal waves
Magnetic fields
Proton density (concentration)
Solar cycle
Solar wind
Wave propagation
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Summary:Voyager 1 has been moving through the very local interstellar medium (VLISM) for approximately one solar cycle, from 122.58 au on 2012/DOY 238 (August 25) to 158.5 au on 2023.0. Previously, an abrupt increase (“jump”) in the magnetic field strength B and proton density N by a factor of 1.35 and 1.36, respectively, was observed during an interval of ∼8 days in 2020.40. After the jump, B continued to increase to a maximum value ∼0.56 nT at ∼2021.4 and then declined until B returned to the postjump value of 0.5 nT on 2021.85, 1.45 yr after the jump. The magnetic field strength declined briefly from 0.5 nT on 2021.85 to 0.47 nT on 2021.95 and then increased sporadically to 0.52 nT at 2023.0. Thus, the magnetic field strength remained strong for at least 2.6 yr. The magnetic hump and the density hump were a compression wave propagating through the VLISM. The compression wave was generated by a region with large dynamic pressure in the solar wind that propagated through the inner heliosheath and collided with the heliopause. The magnetic field strength continued to remain strong, with slow variations, until the end of our observations at 2023.0. It is suggested that the magnetic hump evolved from the large dynamic pressure, high speeds, and density observed at 1 au between ∼2015 and ∼2017.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/acd6eb