  The extension of the corona of classical T Tauri stars (CTTS) is under
discussion. The standard model of magnetic configuration of CTTS predicts that
coronal magnetic flux tubes connect the stellar atmosphere to the inner region
of the disk. However, differential rotation may disrupt these long loops. The
results from Hydrodynamic modeling of X-ray flares observed in CTTS confirming
the star-disk connection hypothesis are still controversial. Some authors
suggest the presence of the accretion disk prevent the stellar corona to extent
beyond the co-rotation radius, while others simply are not confident with the
methods used to derive loop lengths. We use independent procedures to determine
the length of flaring loops in stars of the Orion Nebula Cluster previously
analyzed using Hydrodynamic models. Our aim is to disentangle between the two
scenarios proposed. We present a different approach to determine the length of
flaring loops based on the oscillatory nature of the loops after strong flares.
We use wavelet tools to reveal oscillations during several flares. The
subsequent analysis of such oscillations is settle on the Physics of coronal
seismology. Our results likely confirm the large extension of the corona of
CTTS and the hypothesis of star-disk magnetic interaction in at least three
CTTS of the Orion Nebula Cluster. Analyzing oscillations in flaring events is a
powerful tool to determine the physical characteristics of magnetic loops in
coronae in stars other than the Sun. The results presented in this work confirm
the star-disk magnetic connection in CTTS.
