Bow shock

For the similar effect on flying objects in an atmosphere, see Bow shock (aerodynamics).
LL Orionis bow shock in Orion nebula. The star's wind collides with the nebula flow.
Hubble, 1995

In astrophysics, bow shocks are shock waves in regions where the conditions of density and pressure change dramatically due to blowing stellar wind.[1] Bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the magnetopause. For stars, this boundary is typically the edge of the astrosphere, where the stellar wind meets the interstellar medium.[1]

  1. ^ a b Sparavigna, A.C.; Marazzato, R. (10 May 2010). "Observing stellar bow shocks". arXiv:1005.1527 [physics.space-ph].