INVESTIGADORES
VASQUEZ Alberto Marcos
artículos
Título:
The Effect of Proton Temperature Anisotropy on the Solar Minimum Corona and Wind
Autor/es:
VÁSQUEZ, ALBERTO M.; VAN BALLEGOOIJEN, ADRIAAN A.; RAYMOND, JOHN C.
Revista:
ASTROPHYSICAL JOURNAL
Editorial:
The University of Chicago Press
Referencias:
Lugar: Austin, Texas-EEUU; Año: 2003 vol. 598 p. 1361 - 1374
ISSN:
0004-637X
Resumen:
A semiempirical, axisymmetric model of the solar minimum corona is
developed by solving the equations for conservation of mass and momentum
with prescribed anisotropic temperature distributions. In the
high-latitude regions, the proton temperature anisotropy is strong and
the associated mirror force plays an important role in driving the fast
solar wind; the critical point where the outflow velocity equals the
parallel sound speed (v=c∥) is reached already at 1.5
Rsolar from Sun center. The slow wind arises from a region
with open-field lines and weak anisotropy surrounding the equatorial
streamer belt. The model parameters were chosen to reproduce the
observed latitudinal extent of the equatorial streamer in the corona and
at large distance from the Sun. We find that the magnetic cusp of the
closed-field streamer core lies at about 1.95 Rsolar. The
transition from fast to slow wind is due to a decrease in temperature
anisotropy combined with the nonmonotonic behavior of the nonradial
expansion factor in flow tubes that pass near the streamer cusp. In the
slow wind, the plasma β is of order unity and the critical point
lies at about 5 Rsolar, well beyond the magnetic cusp. The
predicted outflow velocities are consistent with O5+ Doppler
dimming measurements from UVCS/SOHO. We also find good agreement with
polarized brightness (pB) measurements from LASCO/SOHO and H I Lyα
images from UVCS/SOHO.