  AA Dor (LB 3459) is an eclipsing, close binary (P = 0.26d) consisting of a
sdOB primary star and an unseen secondary with an extraordinary small mass. The
secondary is possibly a former planet which may have survived a common-envelope
phase and has even gained mass.
  In order to investigate on an existing discrepancy between the components'
mass derived from NLTE spectral analysis and subsequent comparison to
evolutionary tracks and masses derived from radial-velocity and the eclipse
curves, we performed phase-resolved high-resolution and high-SN spectroscopy
with the UVES attached to the ESO VLT. From the obtained spectra, we have
determined AA Dor's orbital parameters (P = 22600.702 +/- 0.005 sec, A = 39.19
+/- 0.05 km/sec, T0 = 2451917.152690) and the rotational velocity (v = 47 +/- 5
km/sec) of the primary.
