The Deuterium, Oxygen, and Nitrogen Abundance toward LSE 44

• Published in: The Astrophysical journal 2006-02, Vol.638 (2), p.847-859
• Main Authors: Friedman, S. D, Hébrard, G, Tripp, T. M, Chayer, P, Sembach, K. R
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Sciences of the Universe
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/498969

We present measurements of the column densities of interstellar D I, O I, N I, and H sub(2) made with the Far Ultraviolet Spectroscopic Explorer (FUSE) and of H I made with the International Ultraviolet Explorer (IUE) toward the sdO star LSE 44 [(l, b) = (313 37, + 13 49); d= 554 c 66 pc; z = +129 c 15 pc]. This target is among the seven most distant Galactic sight lines for which these abundance ratios have been measured. The H I column density was estimated by fitting the damping wings of interstellar Lya. The column densities of the remaining species were determined with profile fitting analyses and supplemented with curve-of-growth analyses for O I and H sub(2). We find log N(D super(I)) = 15.87 c 0.08, log N (O super(I)) = 17.57 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(2) sub(1) super(1) sub(5), log N(N super(I)) = 16.43 c 0.14, and logN(H super(I)) = 20.52 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(2) sub(3) super(0) sub(6) (all errors 2 s). This implies that D/H = (2.24 super(+) sub(-) super(1) sub(1) super(.) sub(.) super(3) sub(3) super(9) sub(2)) x 10 super(-5), D/O = (1.99 super(+) sub(-) super(1) sub(0) super(.) sub(.) super(3) sub(6) super(0) sub(7)) x 10 super(-2), D/N = (2.75 super(+) sub(-) super(1) sub(0) super(.) sub(.) super(1) sub(8) super(9) sub(9)) x 10 super(-1), and O/H = (1.13 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(9) sub(7) super(6) sub(1)) x 10 super(-3). Of the most distant Galactic sight lines for which the deuterium abundance has been measured, LSE 44 is one of the few with D/H higher than the Local Bubble value, but D/O toward all these targets is below the Local Bubble value and more uniform than the D/H distribution.