English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In 2012, Voyager 1 became the first in situ probe of the very localinterstellar medium. The Voyager 1 Plasma Wave System has given point estimatesof the plasma density spanning about 30 astronomical units (au) of interstellarspace, revealing a large-scale density gradient and compressive turbulenceoutside the heliopause. Previous studies of the plasma density reliedexclusively on the detection of discrete plasma oscillation events that aretriggered ahead of shocks propagating outwards from the Sun, which were used toinfer the plasma frequency and hence density. We present the detection of aclass of very weak, narrowband plasma wave emission in the Voyager 1 PlasmaWave System data that persists from 2017 onwards and enables a steadily sampledmeasurement of the interstellar plasma density over about 10 au with an averagesampling time of 3 days, or 0.03 au. We find au-scale density fluctuations thattrace turbulence in the interstellar medium between episodes of previouslydetected plasma oscillations. Possible mechanisms for the narrowband emissioninclude thermally excited plasma oscillations and quasi-thermal noise, andcould be clarified by new findings from Voyager or a future interstellarmission. The persistence of the emission suggests that Voyager 1 may be able tocontinue tracking the interstellar plasma density in the absence ofshock-generated plasma oscillation events.

Persistent Plasma Waves in Interstellar Space Detected by Voyager 1