A SPECTROPHOTOMETRIC STUDY OF THE ECLIPSING NOVA-LIKE VARIABLE V1315-AQUILAE

We present photometry and spectroscopy of the nova-like variable V1315 Aquilae. The V-band light curves exhibit deep, symmetrical eclipses which recur with a period of 3.35 hr. The spectra have narrow single-peaked Balmer and He I emission lines which, due to absorption of low-velocity emission, exhibit a double-peaked structure near the inferior conjunction of the emission line source. The lack of a primary eclipse in the Balmer and He I lines suggests a non-disc origin for the low-excitation lines. The high-excitation lines of He II lambda-4686 angstrom and C III/N III lambda-lambda-4640-4650 angstrom remain single-peaked at all phases and exhibit a deep primary eclipse, indicating an origin close to the white dwarf. Radial-velocity measurements show large phase shifts in both the low- and high-excitation lines, which by means of Doppler tomography we attribute to contaminating emission around phase 0.75. We review a number of models which have been proposed to explain the above phenomena and comment upon whether they satisfy the constraints placed upon V1315 Aql by our observations. We are able to reject all but two of the proposed hypotheses: an accretion disc wind and an intermediate polar interpretation.