Deuterium in early-type stars. The case of alpha Pavonis.

From the observation of the Hα and Dα lines of the early-type star α Pav, it is shown that the deuterium abundance in its upper atmosphere should be less than 5×10^-6 in number. This either shows that the interstellar medium abundance of deuterium at the time of the α Pav formation was so low (a result marginally compatible with todays observations of the interstellar medium) or that the deuterium was burned in α Pav stellar atmosphere during a pre-main sequence phase. In both cases, this implies a more rapid burning of the deuterium in the Galaxy than it was previously thought.