NOVA-V2214 OPHIUCHI 1988 - A MAGNETIC NOVA INSIDE THE PERIOD GAP

We have discovered a coherent photometric modulation in Nova Oph 1988 with period 0.117515 +/- 0.000002 d (2.82 hr) which we associate to the orbital period of the underlying binary. This places the system at the upper side of the gap of the cataclysmic variables' (CVs) period distribution. The striking similarity of the orbital light curve with that of AM Her and the presence of prominent He II lines in the optical spectrum-similar to the magnetic nova candidates V1500 Cyg, GQ Mus, and CP Pup-strongly suggest that this is also a magnetic nova. Inclusion of this object in the statistics of novae raises an interesting scenario. There are presently four novae with known orbital period P(orb) less than or similar 3 hr, half of which lie in the period pp. All these systems are suspected to harbor magnetic white dwarfs. This evidence suggests (1) that there is no period gap for novae, and (2) that magnetic CVs are strongly favored among novae for P(orb) less than or similar 3.3 hr. Implications and support for these conclusions are discussed in the light of thermonuclear runaway models and the hibernation model of classical novae, and of current models to explain the period gap.