AAS 201st Meeting, January, 2003
Session 77. The Interstellar Medium II
Poster, Wednesday, January 8, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[77.12] Deuterium measurements toward the white dwarf PG~0038+199

G. Williger, C. Oliveira, J. Dupuis (JHU), S. Friedman (STScI)

Primordial deuterium abundance measurements provide a strong constraint on the baryon density in the Universe. When combined with deuterium measurements in the local interstellar medium (ISM), they also provide constraints on models of galactic chemical evolution. Previous D studies have shown that at distances d {\rlap{>}{\lower 1.0ex\sim}}100 pc, there appears to be an increase in spatial variations of D/H. We probe this variation through a measurement of the deuterium abundance from 13 ksec of Far Ultraviolet Spectroscopic Explorer (FUSE) large aperture data of the He-rich white dwarf PG~0038+199 (DO, T=115000~K, log g=7.5, Galactic \ell = 119.79\circ, b=-42.66). At d~300~pc it is one of the more distant objects examined for ISM deuterium studies with FUSE. Keck HIRES data (7~km~s-1 resolution) reveal only one cold ISM component from Na~I. The continuum of PG~0038+199 is not significantly affected by photospheric lines. Its UV flux of 2\times 10-12 erg cm-2 s-1 Å-1 at 1000 Å\ offers a relatively bright background for ISM measurements. We will use a combination of profile fitting and curve of growth methods to measure the column densities of D~I and a variety of other species such as H~I (from the damping wings of Ly\beta using a theoretical stellar model), O~I, H2 etc.

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