The Detection of a 3.5 hr Period in the Classical Nova Velorum 1999 (V382 Vel) and the Long-Term Behavior of the Nova Light Curve

We present CCD photometry, light-curve, and time series analysis of the classical nova V382 Vel (Nova Vel 1999). The source was observed for 2 nights in 2000, 21 nights in 2001, and 7 nights in 2002 using clear filters. We report the detection of a distinct period in the light curve of the nova P = 0.146126(18) days (3.5 hr). The period is evident in all data sets, and we interpret it as the binary period of the system. We also measured an increase in the amplitude modulation of the optical light (in magnitudes) by more than 55% from 2000 to 2001 and about 64% from 2001 to 2002. The pulse profiles in 2001 show deviations from a pure sinusoidal shape that progressively become more sinusoidal by 2002. The main cause of the variations in 2001 and 2002 can be explained with the occultation of the accretion disk by the secondary star. We interpret the observed deviations from a pure sinusoidal shape as additional flux resulting from the aspect variations of the irradiated face of the secondary star.