Multiwavelength Observations of the Hot DB Star PG 0112+104
Abstract
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 sun), 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.
Based on observations with the FUSE satellite, which is operated by the Johns Hopkins University under NASA contract NAS 5-32985; with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555; and with the Kitt Peak National Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2010
- DOI:
- 10.1088/0004-637X/718/2/647
- arXiv:
- arXiv:1006.0365
- Bibcode:
- 2010ApJ...718..647D
- Keywords:
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- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 10 pages in emulateapj, 9 figures, accepted for publication in ApJ