THE DISCOVERY OF VARIABLE POLARIZATION OVER THE 13.9 MINUTE SPIN PERIOD OF THE INTERMEDIATE POLAR RE-0751+14

The total (peak-to-peak) circular polarization variation over the 13.9 minute spin period of RE 0751 + 14 on 1992 October 26 was 4.2% +/- 0. 6% in the I band (830 nm) and 2.2% +/- 0.3% in the R band (690 nm), wi th slightly stronger negative extremes and a faster transition from th e negative to the positive values. The linear polarization reached abo ut 2% in I and 0.8% in R. Our analysis suggests cyclotron emission fro m two extended regions near the opposite magnetic poles of the white d warf, and a field strength B > 5 MG (1 MG = 10(6) G). Fitting the exis ting cyclotron models to the relative amplitudes of the polarization a nd intensity variations in R and I bands required field strengths in t he range 8-18 MG, with the dimensionless plasma parameter of the emiss ion region A = 10(8)-10(5). Larger A values are needed at lower field strengths. The position angle variability could be tentatively explain ed with the inclination of the magnetic white dwarf spin axis i = 45-d egrees-70-degrees and the two cyclotron emission regions 35-degrees-60 -degrees off from the rotational poles. The power spectra of the I- an d R-band intensity modulation are dominated by the cyclotron-originate d spin period peak at 13.9 minutes, but secondary maxima are seen at a pproximately 15 minutes. The UBV bands show maximum modulation at the period of 14.5 minutes, which could be the beat period in the system h aving a binary period of about 5 hr.