We use data obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE ) to determine the interstellar abundances of D I , N I , O I , Fe II , and H _ { 2 } Â along the sightlines to WD 1034 + 001 , BD + 39 3226 , and TD1 32709 .
Our main focus is on determining the D/H , N/H , O/H , and D/O ratios along these sightlines , with log N ( H ) > 20.0 , that probe gas well outside of the Local Bubble . Hubble Space Telescope ( HST ) and International Ultraviolet Explorer ( IUE ) archival data are used to determine the H I column densities along the WD 1034+001 and TD1 32709 sightlines , respectively .
For BD + 39 3226 , a previously published N ( H I ) is used .
We find ( D/H ) \times 10 ^ { 5 } = 2.14 \pm~ { } ^ { 0.53 } _ { 0.45 } , 1.17 \pm~ { } ^ { 0.31 } _ { 0.25 } , and 1.86 \pm~ { } ^ { 0.53 } _ { 0.43 } , and ( D/O ) \times 10 ^ { 2 } = 6.31 \pm~ { } ^ { 1.79 } _ { 1.38 } , 5.62 \pm~ { } ^ { 1.61 } _ { 1.31 } , and 7.59 \pm~ { } ^ { 2.17 } _ { 1.76 } , for the WD 1034 + 001 , BD + 39 3226 , and TD1 32709 sightlines , respectively ( all 1 \sigma ) .
The scatter in these three D/H ratios exemplifies the scatter that has been found by other authors for sightlines with column densities in the range 19.2 < log N ( H ) < 20.7 .
The D/H ratio toward WD 1034 + 001 and all the D/O ratios derived here are inconsistent with the Local Bubble value and are some of the highest in the literature .
We discuss the implications of our measurements for the determination of the present-epoch abundance of deuterium , and for the different scenarios that try to explain the D/H variations .
We present a study of D/H as a function of the average sightline gas density , using the ratios derived in this work as well as ratios from the literature , which suggests that D/H decreases with increasing gas volume density .
Similar behaviors by other elements such Fe and Si have been interpreted as the result of depletion into dust grains .