D/h Measurements

Primordial evaluations of the deuterium abundance should provide one of the best tests of Big Bang nucleosynthesis models. Space as well as ground based observations seem however to result in different values. This asks for more observations in different astrophysical sites in order to link present day interstellar medium D/H evaluations to primordial ones. New investigations, made with FUSE (the Far Ultraviolet Spectroscopic Explorer launched in June 1999), are presented and in the case of the white dwarf G191-B2B line of sight a low D/H evaluation of 1.16±0.24 × 10 −5 (2σ) is confirmed. This seems to indicate that D/H variations are probably present in the nearby interstellar medium. The FUSE observations should help us reach in a near future a better global view of the evolution of that key element.