Deuterium Burning in Substellar Objects

We consider the depletion of primordial deuterium in the interior of substellar objects as a function of mass, age and absolute magnitude in several photometric passbands. We characterize potential spectroscopic signatures of deuterium in the lines of deuterated water HDO. These results will serve as a useful, independent diagnostic to characterize the mass and/or the age of young substellar objects, and to provide an independent age determination of very young clusters. These results can serve to identify objects at the deuteriumburning limit and to confront the theoretical prediction that D-burning is a necessary condition to form star-like objects. Subject headings: stars: low mass, brown dwarfs — stars: interiors — stars: atmosphere — planetary systems — stars: evolution – 3 – 1.