Expansion of the solar wind in high-speed streams

Abstract

view Abstract Citations (27) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Expansion of the solar wind in high-speed streams. Whang, Y. C. ; Chien, T. H. Abstract The expansion of the solar wind in streamtubes with rapid divergence in their supersonic section can be shown to accelerate the wind to a speed of 600 km per sec or more at 1 AU. In a streamtube with a cross-sectional area in the supersonic section which increases more rapidly than the square of the heliocentric distance, the extra area expansion produces a solar wind at a higher Mach number at 1 AU than does normal spherical expansion. The energy needed for the kinetic energy of a high-speed solar wind must be deposited at the base of the solar corona mainly in the form of convective thermal energy and conduction heat. This requires a temperature of about 2.5-4.5 million K at the source region of the sun's surface for the high-speed streams. The acceleration of the solar wind due to Alfven waves which propagate according to the WKB solution, whose effect is one order of magnitude less than the effect of rapid divergence in the supersonic section of streamtubes, is also studied. Publication: The Astrophysical Journal Pub Date: April 1978 DOI: 10.1086/156033 Bibcode: 1978ApJ...221..350W Keywords: Interplanetary Medium; Magnetohydrodynamic Waves; Solar Wind Velocity; Thermal Conductivity; Gas Expansion; Solar Corona; Supersonic Flow; Wentzel-Kramer-Brillouin Method; Solar Physics; Alfven Waves:Solar Wind; Expansion:Solar Wind full text sources ADS |