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

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https://iopscience.iop.org/article/10.3847/1538-4357/acd6eb

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https://doi.org/10.3847/1538-4357/acd6eb
 http://hdl.handle.net/11603/29442

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UMBC Goddard Planetary Heliophysics Institute (GPHI)
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https://orcid.org/0000-0002-8989-4631

Date

2023-08-10

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journal articles
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Citation of Original Publication

Burlaga, L. F., N. Pogorelov, L. K. Jian, J. Park, A. Szabo, and N. F. Ness. “A Large Magnetic Hump in the VLISM Observed by Voyager 1 in 2020–2022.” The Astrophysical Journal 953, no. 2 (August 2023): 135. https://doi.org/10.3847/1538-4357/acd6eb.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

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.