Shocks

1. Shocks Condensation of water vapour into droplets at the sonic shock Supersonic shockvbullet = 1.5 vsound EF2245 Space Physics 2009

2. Solar wind termination shock Bow shock in front of magnetosphere Shocks in space Bow shock at young star LL Ori Supernova remnants (SNR) EF2245 Space Physics 2009

3. Shocks DOWNSTREAM: subsonic relative velocity UPSTREAM: supersonic relative velocity EF2245 Space Physics 2009

4. Definition of shock A shock is a transition layer across which there is a transport of particles and an abrupt, irreversible, nearly discontinuous change in the characteristics of the medium, in particular a change from supersonic to subsonic speed. EF2245 Space Physics 2009

5. Rankine-Hugoniot shock jump conditions (5.1) (5.2) (5.3) (5.4) (5.5) (5.6) EF2245 Space Physics 2009

6. KTH, 2009-09-29 Earth’s magnetosphere Magnetopause crossing Magnetosphere Magnetopause Bow shock 2003-02-02 Magnetosheath Solar wind B (nT) Ne (cm-3) UT (h) Cluster data, [Asikainen, 2006]

7. Cluster • Launched 2000 • Apogee: 20 RE • Perigee: 4 RE • Separations: 200-10000 km EF2240 Space Physics 2009

8. Cluster data from bow shock EF2245 Space Physics 2009

9. Classification of shocks and discontinuities (upstream values!) Discontinuities Shocks: un≠ 0 un Contact discontinuity: Bn≠ 0, un= 0 Parallel shock: Bt= 0, un≠ 0 B un B B un Perpendicular shock: Bn= 0, un ≠ 0 Tangential discontinuity: Bn= 0, un= 0 B un Oblique shock: Bn≠ 0, Bt≠ 0, un ≠ 0 un B B p Fast shock: Rotational discontinuity: Bn= 0, un≠ 0 Field and flow change direction, but not magnitude p Slow shock: B EF2245 Space Physics 2009

10. EF2245 Space Physics 2009