Issue |
A&A
Volume 412, Number 1, December II 2003
|
|
---|---|---|
Page(s) | 293 - 304 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20031413 | |
Published online | 25 November 2003 |
Coronal Mass Ejection (CME)-induced shock formation, propagation and some temporally and spatially developing shock parameters relevant to particle energization
1
Jet Propulsion Laboratory, California Institute of Technology Pasadena, CA, USA
2
Center for Space Plasma and Aeronomic Research The University of Alabama in Huntsville, Huntsville, AL 35899, USA
3
NOAA Space Environment Center, 325 Broadway, Boulder, CO 80305, USA
Corresponding author: S. T. Wu, wus@cspar.uah.edu
Received:
10
June
2003
Accepted:
11
September
2003
Interplanetary shocks accelerate solar energetic particles (SEPs) from the
point
of shock formation in the lower corona, and continuously as the shock
propagates
outward to 1 AU and beyond. In this study, the formation properties of
a CME-induced shock and propagation characteristics are
studied
from the inner corona to 1 AU. We use a 2D, three-component (i.e., 2.5D),
time-dependent MHD code in our model. A well-studied CME event (the 1997
January
6-12 Sun-Earth Connection Event) is used as a baseline for this study. The
solar wind conditions measured at 1 AU (WIND data) are used to motivate our
effort to model the CME driven shock. It is found that the fast forward shock
forms originally at ~3.2 (solar radii) from the
solar surface in the
ecliptic plane for the assumed CME and background solar wind parameters. In
our model, this occurs ~2 hrs after CME initiation. The
shock formation at higher (~30°) latitudes measured from the
ecliptic plane is further from the Sun (~3.6
)
because of higher local magnetosonic speeds that must be exceeded by the
original disturbance for shock formation.
Finally, the shock becomes symmetric at 16
.
In the ecliptic plane at 16
the fast shock Mach
number (
) is ~3.5, and at 30° latitude,
, considerably weaker. A maximum
in the fast shock Mach number of 4 is reached at 130
in the ecliptic
plane. The
decreases to 3.5 by 1 AU.
Other properties of the shock, as well
as its relationship to the local interplanetary properties through which it
passes, are discussed. The interplanetary counterpart, ICME, of the coronal CME, is also discussed. These shock properties, we believe, are relevant to the
shock's ability to accelerate particles to energies as high as 100 MeV. The
actual physical process, however, is not discussed in this paper.
Key words: Sun: corona / Sun: interplanetary shocks / Sun: CME / Sun: MHD
© ESO, 2003
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