Astronomy & Astrophysics

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Issue		A&A Volume 368, Number 3, March IV 2001
Page(s)		L21 - L24
Section		Letters
DOI		10.1051/0004-6361:20010183

A&A 368, L21-L24 (2001)
DOI: 10.1051/0004-6361:20010183

A new deuterium abundance measurement from a damped Ly $\alpha$ system at $\vec{z}_{\mathsf{abs}} =\mathsf$

S. D'Odorico¹, M. Dessauges-Zavadsky^{1, 2} and P. Molaro³

¹ European Southern Observatory, Karl-Schwarzschildstr. 2, 85748 Garching bei München, Germany
² Observatoire de Genève, 1290 Sauverny, Switzerland
³ Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy

(Received 20 November 2000 / Accepted 1 February 2001 )

Abstract
We present the first D/H measurement in a damped Ly $\alpha$ (hereafter DLA) system at $z_{\rm abs} = 3.025$ towards QSO 0347-3819 obtained from the UVES-VLT spectra. The DLA absorber has a metallicity of [Zn/H] $\approx -1.25$ and a relatively simple velocity structure, with two dominating components detected in several metal lines. The hydrogen Lyman series can be followed down to Ly12 thanks to the high UV-Blue efficiency of UVES. The best fit of the Lyman series lines, and in particular of Ly $\epsilon$ , Ly8, Ly10 and Ly12, relatively free of local contamination, is obtained when the DI absorption is included in the two main components. The measured deuterium column density yields $\frac{\rm D}{\rm H} = (2.24\pm 0.67) 10^$ close to other low D/H values from Lyman limit systems. The corresponding values for the baryon to photon ratio and the baryon density derived from D/H are $\eta \approx 6 10^$ and $\Omega_{\rm b} h^2 = 0.023$ respectively.

Key words: cosmology: observations -- quasars: QSO 0347 -- 3819 -- nuclear reactions, nucleosynthesis, abundances

Offprint request: S. D'Odorico, sdodoric@eso.org

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A new deuterium abundance measurement from a damped Ly system at

A new deuterium abundance measurement from a damped Ly $\alpha$ system at $\vec{z}_{\mathsf{abs}} =\mathsf$