The heliopause is where the Solar wind is counter balanced by the particle winds from other stars. This boundary seems to not be spherical and also to fluctuate in shape.

Can the shape of the heliopause be estimated by the pressure from surrounding stars and open clusters?

Can the fluctuations be attributed to specific stars in the Solar neighborhood? Are there single stars both so active and so nearby that they dominate the fluctuations of the Heliopause? Did Voyager in effect observe the effects of a specific event on a specific star's surface when the heliopause boundary billowed back and forth over it?

  • $\begingroup$ The heliopause extends about twice the distance of Pluto or 1/1000th of a light year. It seems to be most affected by streams of charged particles, not other stars. My guess would be no, it's not affected much by near-by stars, but I'm just guessing. The Milkyway might have a magnetic field that affects it, but I don't think the effect from nearby stars is all that much. Studying the magnetic fields beyond our solar system, is a new field however. A lot is still unknown. $\endgroup$
    – userLTK
    Oct 15, 2017 at 7:30
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    $\begingroup$ I don't have the resources right now to look up to back this up, but calculations for the heliopause/bow shock always assume the pressure which the solar wind is fighting against is the the ISM pressure. $\endgroup$
    – zephyr
    Oct 16, 2017 at 14:07

1 Answer 1


The heliopause oscillates due to changes in the solar wind (i.e., speed and density) and changes in the local interstellar medium (i.e., speed and density). The next largest influence comes from what are called pick-up ions, which exert an effective pressure on the termination shock etc. These act kind of like cosmic rays do on supernova, i.e., they modify the shock jump conditions significantly. All other effects are of much smaller order on the overall shape and size and dynamics.


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