2002ApJS..140...37F

We present measurements of the column densities of interstellar D I and O I made with the Far Ultraviolet Spectroscopic Explorer (FUSE) and of H I made with the International Ultraviolet Explorer (IUE) toward the sdOB star Feige 110 [(l,b)=(74°.09,-59°.07); d=179⁺²⁶⁵_–67 pc; z=-154⁺⁵⁷_–227 pc]. Our determination of the D I column density made use of curve-of-growth fitting and profile fitting analyses, while our O I column density determination used only curve-of-growth techniques. The H I column density was estimated by fitting the damping wings of the interstellar Lyα profile. We find logN(DI)=15.47±0.06, logN(OI)=16.73±0.10, and logN(HI)=20.14^+0.13_–0.20 (all errors 2 σ). This implies D/H=(2.14±0.82)x10^–5, D/O=5.50^+1.64_–1.33x10^–2, and O/H=(3.89±1.67)x10^–4. Taken with the FUSE results reported in companion papers and previous measurements of the local interstellar medium (LISM), this suggests the possibility of spatial variability in D/H for sight lines exceeding ∼100 pc. This result may constrain models which characterize the mixing timescales and length scales of material in the LISM.