The eclipsing intermediate polar V597 Pup (Nova Puppis 2007)

Photometric observations of V597 Pup made in 2008, 9.1 mag below maximum, 4 months after eruption, showed no certain orbital modulation but exhibited a quintuplet of oscillations centred on a period 261.9 s and uniform splitting at a frequency ∼2.68 h⁻¹. One year later, the system had fallen in brightness by a further 2.5 mag, showed deep eclipses with a period of 2.6687 h, and the 261.9 s modulation at a reduced amplitude. There is often power near the ‘subharmonic’ at 524 s showing that the shorter periods observed are actually first harmonics.

V597 Pup is thus an intermediate polar, and is in the ‘orbital period gap’. Furthermore, it is the first to show a prominent secondary eclipse, caused by passage of the optically thick disc in front of the irradiated side of the secondary star.