  Classical T Tauri stars (CTTS) are surrounded by actively accreting disks.
According to current models material falls along the magnetic field lines from
the disk with more or less free-fall velocity onto the star, where the plasma
heats up and generates X-rays. We want to quantitatively explain the observed
high energy emission and measure the infall parameters from the data. Absolute
flux measurements allow to calculate the filling factor and the mass accretion
rate.We use a numerical model of the hot accretion spot and solve the
conservation equations. A comparison to data from XMM-Newton and Chandra shows
that our model reproduces the main features very well. It yields for TW Hya a
filling factor of 0.3% and a mass accretion rate 2e-10 M_sun/yr.
