The Inability of Steady Flow Models to Explain the EUV Coronal Loops
Spiros Patsourakos Submitted: 2003-12-03 11:43
Recent observations from TRACE and EIT show that warm (1-1.5 MK)
EUV coronal loops in active regions generally have enhanced densities,
enhanced pressure scale heights, and flat filter ratio
profiles in comparison
with the predictions of static equilibrium theory.
It has been suggested that mass flows
may explain these discrepancies.
We investigate this conjecture using
1D hydrodynamic simulations of steady flows in coronal loops.
The flows are driven by asymmetric heating
that decreases exponentially along the loop
from one footpoint to the other.
We find that a sufficiently large heating asymmetry can
produce density enhancements consistent with a sizable
fraction of the observed loops, but that the
pressure scale heights are smaller than the corresponding
gravitational scale heights and that the filter ratio
profiles are highly structured, in stark contrast with
the observations. We conclude that most warm EUV loops cannot be
explained by steady flows. It is thus likely that the heating in these
loops is time dependent.
Authors: S. Patsourakos, J. A. Klimchuk & P. J. MacNeice
Publication Status: ApJ (in press)
Last Modified: 2003-12-03 11:43