Nova Velorum 1999 (V382 Vel) was observed by BeppoSAX 6 months after optical
maximum and was detected as a bright X-ray supersoft source, with a count rate
3.454+-0.002 cts/s in the LECS. It was the softest and most luminous supersoft
source observed with this instrument. The flux in the 0.1-0.7 keV range was not
constant during the observation. It dropped by a factor of 2 in less than 1.5
hour and then was faint for at least 15 minutes, without significant spectral
changes.
The observed spectrum is not well fit with atmospheric models of a hot,
hydrogen burning white dwarf. This is due mainly to a supersoft excess in the
range 0.1-0.2 keV, but the fit can be significantly improved at higher energy
if at least one emission feature is superimposed. We suggest that a
``pseudocontinuum'' was detected, consisting of emission lines in the supersoft
X-ray range superimposed on the thermal continuum of a white dwarf atmosphere.
As a result, an accurate determination of the effective temperature and gravity
of the white dwarf at this post-outburst stage is not possible.Comment: To appear in MNRA