Deuterium Abundance toward WD 1634-573: Results from the FUSE Mission
Abstract
We use Far Ultraviolet Spectroscopic Explorer (FUSE) observations to study interstellar absorption along the line of sight to the white dwarf WD 1634-573 (d=37.1+/-2.6 pc). Combining our measurement of D I with a measurement of H I from Extreme Ultraviolet Explorer data, we find a D/H ratio toward WD 1634-573 of D/H=(1.6+/-0.5)×10-5. In contrast, multiplying our measurements of DI/OI=0.035+/-0.006 and DI/NI=0.27+/-0.05 with published mean Galactic interstellar medium (ISM) gas-phase O/H and N/H ratios yields D/HO=(1.2+/-0.2)×10-5 and D/HN=(2.0+/-0.4)×10-5, respectively. Note that all uncertainties quoted above are 2 σ. The inconsistency between D/HO and D/HN suggests that either the O I/H I or the N I/H I ratio toward WD 1634-573 must be different from the previously measured average ISM O/H and N/H values. The computation of D/HN from D I/N I is more suspect, since the relative N and H ionization states could conceivably vary within the local ISM, while the O and H ionization states will be more tightly coupled by charge exchange. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by Johns Hopkins University under NASA contract NAS 5-32985.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- May 2002
- DOI:
- 10.1086/339127
- arXiv:
- arXiv:astro-ph/0112296
- Bibcode:
- 2002ApJS..140...91W
- Keywords:
-
- ISM: Abundances;
- Stars: Individual: Alphanumeric: WD 1634-573;
- Ultraviolet: ISM;
- Stars: White Dwarfs;
- Astrophysics
- E-Print:
- 23 pages, 5 figures