X-ray spectra of the late-type star AB Dor , obtained with the XMM-Newton satellite are analysed .
AB Dor was particularly active during the observations .
An emission measure reconstruction technique is employed to analyse flare and quiescent spectra , with emphasis on the Fe XVII 15 - 17 Å wavelength region .
The Fe XVII 16.78 Å/15.01 Å line ratio increases significantly in the hotter flare plasma .
This change in the ratio is opposite to the theoretical predictions and is attributed to the scattering of 15.01 Å line photons from the line-of-sight .
The escape probability technique indicates an optical depth of \approx 0.4 for the 15.01 Å line .
During the flare , the electron density is 4.4 ^ { +2.7 } _ { -1.6 } \times 10 ^ { 10 } cm ^ { -3 } and the fractional Fe abundance is 0.5 \pm 0.1 of the solar photospheric value ( 8 ) .
Using these parameters a path length of \approx 8,000 km is derived .
There is no evidence for opacity in the quiescent X-ray spectrum of the star .