  Using high resolution UVES spectra of the eclipsing Post Common Envelope
Binary QS Vir we detect material along the line of sight to the white dwarf at
orbital phase $\phi=0.16$. We ascribe this to a stellar prominence originating
from the M dwarf secondary star which passes in front of the white dwarf at
this phase. This creates sharp absorption features in the hydrogen Balmer
series and Ca II H and K lines. The small size of the white dwarf allows us to
place tight constraints on the column density of hydrogen in the n=2 level of
log_(10)(N_2) = 14.10 +/- 0.03 cm^(-2) and, assuming local thermodynamical
equilibrium, the temperature of the prominence material of ~9000K. The
prominence material is at least 1.5 stellar radii from the surface of the M
dwarf. The location of the prominence is consistent with emission features
previously interpreted as evidence for Roche lobe overflow in the system. We
also detect Mg II 4481A absorption from the white dwarf. The width of the Mg II
line indicates that the white dwarf is not rapidly rotating, in contrast to
previous work, hence our data indicate that QS Vir is a pre-cataclysmic binary,
yet to initiate mass transfer, rather than a hibernating cataclysmic variable
as has been suggested.
