Résumé
The abundance derivation of heavy r-elements may provide a better understanding of the r-process, and the determination of several reference r-elements should allow a better determination of the star's age. The spatial ultraviolet (UV) region presents a large number of lines of heavy elements, and in some cases such as Bi, Pt, Au, detectable lines are only available in the UV. The extreme ``r-process star'' CS 31082-001 ([Fe/H] = -2.9) was observed in the spatial UV in order to determine abundances of the heavy elements, using STIS on board HST.