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 theclassical nova V382 Vel (N Vel 1999). The source was observed for 2 nights in2000, 21 nights in 2001 and 7 nights in 2002 using clear filters. We report thedetection of a distinct period in the light curve of the nova P=0.146126(18) d(3.5 h). The period is evident in all data sets, and we interpret it as thebinary period of the system. We also measured an increase in the amplitudemodulation of the optical light (in magnitude) by more than 55% from 2000 to2001 and about 64% from 2001 to 2002. The pulse profiles in 2001 showdeviations from a pure sinusoidal shape which progressively become moresinusoidal by 2002. The main cause of the variations in 2001 and 2002 can beexplained with the occultation of the accretion disk by the secondary star. Weinterpret the observed deviations from a pure sinusoidal shape as additionalflux resulting from the aspect variations of the irradiated face of thesecondary star.Comment: 16 pages and 4 figures, accepted as it stands to be published in the Astronomical Journal (AJ