The continuum variability of the puzzling X-ray three-period cataclysmic variable 2A 0526-328 (TV Col).

Abstract

TV Col is characterized on the basis of 120-195-nm and 190-320-nm large-aperture low-dispersion IUE spectra obtained between April 1980 and May 1982, UBV measurements obtained with the 1-m telescope at ESO in November 1979 (Motch, 1981), and JHK photometry obtained using the standard IR photometer on the 3.6-m telescope at ESO on Dec. 31, 1982. The variations of the UV flux and of the optical flux at 365 nm are found to be modulated with the 5.5-h spectroscopic period, with a UV/optical energy distribution (for that period and the 5.2-h photometric period) which is consistent with blackbody components at 16,000 and 11,000 K, respectively. The secondary is considered to be a 4300-K object of radius 0.75 solar radius at distance 500 pc; the 5.5-h modulation is attributed to an X-ray-illuminated bulge on the accretion disk; and a model involving a disk precessing in retrograde direction with period 4 d is proposed to explain both the 4-d and the 5.2-h periodicities.