Very local interstellar medium

Assembled from 12 blocks · 2 evidence · 7 related

1. Story
2. The gas, dust, magnetic field and cosmic rays immediately outside the heliosphere — the material the Sun is currently moving through, sometimes called the Local Interstellar Cloud. The Voyagers are the only instruments that have ever sampled it in situ, and what they found did not match expectation. The plasma is denser than the solar wind at the same distance but still extraordinarily thin, of order a tenth of a particle per cubic centimetre. Voyager 2 measured it hotter than models predicted — of order 30,000 to 50,000 kelvin against a prediction nearer 15,000 to 30,000 — and found variable currents just outside the boundary. The magnetic field direction outside turned out to be close to the direction inside, which was not expected and complicated the interpretation of Voyager 1's crossing at the time. Not a place.
3. Knowledge
4. Very local interstellar medium
5. Connections
6. Heliosphere
7. Heliopause
8. Voyager 1 crosses the heliopause at 121.6 AU
9. Voyager 2 crosses the heliopause at 119 AU
10. Evidence
11. Voyager 2 crossed the heliopause on 5 November 2018 at 119 AU; a boundary layer about 1.5 AU wide preceded it in which the plasma slowed, heated and was roughly twice as dense as typical heliosheath plasma; the transition took less than a day, and the interstellar plasma immediately outside was hotter than predicted, of order 30,000–50,000 °C against a prediction nearer 15,000–30,000 °C. V55 verification basis: the paper was not fetched — nature.com is blocked to this session — but search results carried these figures and attributed them to it.
12. Voyager 1's plasma wave instrument recorded electron plasma oscillations near 2.6 kHz in October–November 2012 and April–May 2013, implying an electron density of about 0.08 cm⁻³ and indicating that the spacecraft had been in interstellar plasma continuously since the boundary crossings of July–August 2012, dated 25 August 2012 at 121.6 AU. V55 verification basis: the paper is on a publisher domain blocked to this session, but search results carried the frequency, the density and the crossing date and distance and attributed them to this paper.