Hydrodynamics of the Solar Wind Expansion

Why is the solar wind supersonic?
  • M. Velli
Conference paper


A pedagogical introduction to the classical hydrodynamic steady state solutions for flows in a spherically symmetric atmosphere is presented along with a detailed analysis of the stability of such flows and a discussion of the Parker/Bondi phase diagram of solutions in the Mach number — stellar radius plane. This leads naturally to the scenario presented by (1994) for wind-accretion transitions, which helps to explain results from numerical simulations in many contexts and gives a more comprehensive answer to the question of why the solar wind and other steady state flows in spherical symetry must quite generally become supersonic.


Solar Wind Mach Number Stellar Wind Transonic Flow Sonic Point 
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Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • M. Velli
    • 1
  1. 1.Dipartimento di Astronomia e Scienze dello SpazioUniversità di FirenzeItaly

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