Dm. Meyer et al., THE ABUNDANCE OF INTERSTELLAR OXYGEN TOWARD ORION - EVIDENCE FOR RECENT INFALL, The Astrophysical journal, 437(1), 1994, pp. 120000059-120000061
We present high S/N (> 800) Goddard High-Resolution Spectrograph obser
vations of the weak interstellar O I] lambda 1356 absorption in the lo
w-density sight lines toward iota Ori and kappa Ori. By comparing thes
e data with observations toward more reddened stars, we find no eviden
ce of density-dependent depletion from the gas phase for oxygen. The d
erived total oxygen abundance (gas plus grains) toward iota Ori and ka
ppa Ori is consistent with stellar and nebular determinations in Orion
at a level that is one-half the solar value. We speculate that the O/
H abundance ratio is lower in Orion compared to the Sun because the lo
cal Milky Way has suffered a recent infall of metal-poor material, per
haps from the Magellanic Stream.