Abstract
We present accurate CCD spectropolarimetry and spectra that show that the hot DB star LB 8827 (PG 0853+164) is a weakly magnetic, variable DBA white dwarf. We confirm Putney's detection of circular dichroism in the He I lines, but on three occasions we measure a weaker field strength and opposite sign of circular polarization, Be 100 kG. The Balmer line strengths appear to vary with time, indicative of changes in the apparent H/He abundance ratio or irregularities over the stellar surface. Fits to the observed energy distribution and to the optical He I line spectrum with model atmospheres yield effective temperatures in the 21,200-27,700 K range, with lower values favored. This suggests that LB 8827 falls within or near the instability strip of the V777 Herculis stars. High time resolution photometric observations presented here rule out white-light brightness variations with amplitudes larger than 1.2 mmag in the period window 20 s to 2 hr. The possibility that the magnetic field might tend to suppress pulsations is discussed.
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