Evidence for Deuterium Astration in the Planetary Nebula Sh 2-216?

We present FUSE observations of the line of sight to WD0439+466 (LS V +4621), the central star of the old planetary nebula Sh2-216. The FUSE data showsabsorption by many interstellar and stellar lines, in particular D I, H2 (J = 0- 9), HD (J = 0 - 1), and CO. Many other stellar and ISM lines are detected inthe STIS E140M HST spectra of this sightline, which we use to determine N(HI).We derive, for the neutral gas, D/H=(0.76 +0.12 -0.11)E-5, O/H = (0.89 +0.15-0.11)E-4 and N/H = (3.24 +0.61-0.55)E-5. We argue that most of the gas alongthis sightline is associated with the planetary nebula. The low D/H ratio islikely the result of this gas being processed through the star (astrated) butnot mixed with the ISM. This would be the first time that the D/H ratio hasbeen measured in predominantly astrated gas. The O/H and N/H ratios derivedhere are lower than typical values measured in other planetary nebulae likelydue to unaccounted for ionization corrections.Comment: Accepted for publication is ApJ