PRIMORDIAL MOLECULES IN A MODEL OF GRAVITATIONAL COLLAPSE

It is now well known that a primordial chemistry, involving light elements produced during the nucleosynthesis period might develop during the hydrogen post-recombination era. In particular, molecular ions and primordial molecules such as H-2, HD and LiH will be produced. We summarize this primordial chemistry after the recombination epoch, and then present a simple gravitational collapse model of a cloud (M = 10(9) M.) including molecules. As a result, abundances are seen to be modified during the collapse where in particular the HD abundance is considerably lowered while H-2 and LiH productions are correspondingly enhanced. We discuss these evolutions and present what, in our opinion, could be further developed and clarified from this simple model.