Deuterium and oxygen toward Feige 110:: Results from the FUSE mission

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.degrees09, -59.degrees07); d = 179(-67)(+265) pc; z = 154(-227)(+57) pc]. Our determination of the D I column density made use of curve-of-growth fitting and pro letting 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 Lyalpha profile. We find log N( D I) = 15.47 +/- 0.06, log N (O I) = 16.73 +/- 0.10, and log N (H I) = 20.14(-0.20)(+0.13) (all errors 2sigma). This implies D/H = (2.14 +/- 0.82) x 10(-5), D/O = (5.50(-1.33)(+1.64)) x 10(-2), and O/H = (3.89 +/- 1.67) x 10(-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 similar to100 pc. This result may constrain models which characterize the mixing timescales and length scales of material in the LISM.