Multiwavelength Observations of the Hot Db Star Pg 0112+104

We present a comprehensive multiwavelength analysis of the hot DB white dwarf PG 0112+104. Our analysis relies on newly acquired FUSE observations, on medium-resolution FOS and GHRS data, on archival high-resolution GHRS observations, on optical spectrophotometry both in the blue and around Hα, as well as on time-resolved photometry. From the optical data, we derive a self-consistent effective temperature of 31,300 ± 500 K, a surface gravity of log g = 7.8 ± 0.1 ( M = 0.52 M ☉ ), and a hydrogen abundance of log N (H)/ N (He)< −4.0. The FUSE spectra reveal the presence of C ii and C iii lines that complement the previous detection of C ii transitions with the GHRS. The improved carbon abundance in this hot object is log N (C)/ N (He) = −6.15 ± 0.23. No photospheric features associated with other heavy elements are detected. We reconsider the role of PG 0112+104 in the definition of the blue edge of the V777 Her instability strip in light of our high-speed photometry and contrast our results with those of previous observations carried out at the McDonald Observatory.