Ar. Winebarger et al., Apparent flows above an active region observed with the Transition Region and Coronal Explorer, ASTROPHYS J, 553(1), 2001, pp. L81-L84
The Transition Region and Coronal Explorer (TRACE) observed Active Region 8
395 on 1998 December 1 from 1:30:00 to 3:00:00 UT at high cadence in the Fe
IX/Fe x channel (log T-e approximate to 6.0). Throughout the observing tim
e, brightness Variations along a dense bundle of coronal field lines in the
southwest corner of the active region were observed. Movies made of this r
egion give the impression of continuous intermittent outflow in this bundle
of coronal loops; such apparent outflow is often seen in the TRACE data. I
n this Letter, we present an analysis of four separate flow events occurrin
g in three different loops. These events are used as tracers of the how in
order to characterize its physical properties, such as apparent velocity. T
he projected velocities of the intensity fronts of these flows land hence l
ower limits of true velocities) are between 5 and 20 Inn s(-1). Comparisons
of the observed intensities with those predicted by a quasi-static model s
uggest that the events can be explained only by a mass flow from the chromo
sphere into the corona. The persistence of the hows, and their ubiquity in
the TRACE observations, indicates that hydrostatic loops models are not app
licable to this class of coronal structures.