2003ApJ...591.1000A

We present new measurements of the interstellar gas-phase oxygen abundance along the sight lines toward 19 early-type Galactic stars at an average distance of 2.6 kpc. We derive O I column densities from Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) observations of the weak 1355 Å intersystem transition. We derive total hydrogen column densities [N(HI)+2N(H₂)] using HST/STIS observations of Lyα and Far Ultraviolet Spectroscopic Explorer (FUSE) observations of molecular hydrogen. The molecular hydrogen content of these sight lines ranges from f(H₂)=2N(H₂)/[N(HI)+2N(H₂)]=0.03 to 0.47. The average <H_tot/E_B–V> of 6.3x10²¹ cm^–2 mag^–1 with a standard deviation of 15% is consistent with previous surveys. The mean oxygen abundance along these sight lines, which probe a wide range of Galactic environments in the distant interstellar medium, is 10⁶ (O/H)_gas=408±13 (1 σ in the mean). We see no evidence for decreasing gas-phase oxygen abundance with increasing molecular hydrogen fraction, and the relative constancy of (O/H)_gassuggests that the component of dust containing the oxygen is not readily destroyed. We estimate that, if 60% of the dust grains are resilient against destruction by shocks, the distant interstellar total oxygen abundance can be reconciliated with the solar value derived from the most recent measurements of 10⁶ (O/H)_gas☉=517±58 (1 σ). We note that the smaller oxygen abundances derived for the interstellar gas within 500 pc or from nearby B star surveys are consistent with a local elemental deficit.