Journal article
Persistent plasma waves in interstellar space detected by Voyager 1
NATURE ASTRONOMY, Vol.5(8), pp.761-765
08/01/2021
DOI: 10.1038/s41550-021-01363-7
PMCID: PMC8740711
PMID: 35005245
Abstract
In 2012, Voyager 1 became the first in situ probe of the very local interstellar medium(1). The Voyager 1 Plasma Wave System has given point estimates of the plasma density spanning about 30 au of interstellar space, revealing a large-scale density gradient(2,3) and turbulence(4) outside of the heliopause. Previous studies of the plasma density relied on the detection of discrete plasma oscillation events triggered ahead of shocks propagating outwards from the Sun, which were used to infer the plasma frequency and, hence, density(5,6). We present the detection of a class of very weak, narrowband plasma wave emission in the Voyager 1 data that persists from 2017 onwards and enables a steadily sampled measurement of the interstellar plasma density over about 10 au with an average sampling distance of 0.03 au. We find au-scale density fluctuations that trace interstellar turbulence between episodes of previously detected plasma oscillations. Possible mechanisms for the narrowband emission include thermally excited plasma oscillations and quasi-thermal noise, and they could be clarified by new findings from Voyager or a future interstellar mission. The emission's persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events.
The Voyager 1 spacecraft is now probing interstellar space beyond the heliopause. Here, measurements from the Plasma Wave System reveal au-scale density fluctuations that trace interstellar turbulence without the need for solar shock-generated plasma oscillation events.
Details
- Title: Subtitle
- Persistent plasma waves in interstellar space detected by Voyager 1
- Creators
- Stella Koch Ocker - Planetary Science InstituteJames M. Cordes - Cornell UniversityShami Chatterjee - Cornell UniversityDonald A. Gurnett - University of IowaWilliam S. Kurth - University of IowaSteven R. Spangler - University of Iowa
- Resource Type
- Journal article
- Publication Details
- NATURE ASTRONOMY, Vol.5(8), pp.761-765
- DOI
- 10.1038/s41550-021-01363-7
- PMID
- 35005245
- PMCID
- PMC8740711
- NLM abbreviation
- Nat Astron
- ISSN
- 2397-3366
- eISSN
- 2397-3366
- Publisher
- NATURE PORTFOLIO
- Number of pages
- 5
- Grant note
- 80NSSC20K0784 / National Aeronautics and Space Administration (NASA); National Aeronautics & Space Administration (NASA) PHY-1430284 / NSF; National Science Foundation (NSF) 1622510 / NASA; National Aeronautics & Space Administration (NASA) AAG-1815242 / National Science Foundation (NSF); National Research Foundation of Korea Jet Propulsion Laboratory
- Language
- English
- Date published
- 08/01/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455553002771
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