The cold envelopes and the hot corinos of solar type protostars
Cecilia CECCARELLI
LAOG, Grenoble
Résumé :
Last years have seen substantial progresses in our
understanding of the solar type protostars structure,
and particularly of the chemical structure of the protostellar
envelopes. On the one hand, the cold outer regions keep intact
the memory of the past pre-collapse phase, when the dust is
so cold and dense that almost all molecules freeze out onto
the dust grain mantles. The gas chemical composition
undergoes dramatic changes, whose the most spectacular aspect
is the huge increase of the molecular deuteration degree,
which can reach 8 orders of magnitudes with respect to the
elemental D/H ratio.On the other hand, in the innermost regions
of the envelope -the so-called hot corinos- the grain
mantles evaporate, when the dust temperatures exceeds 100K,
injecting in the gas phase plenty of hydrogenated molecules,
like formaldehyde and methanol. Those molecules probably
undergo chemical reactions which form more complex, organic
molecules, now observed also in the low mass hot corinos.
Puzzling enough, the involved timescales seem to be much shorter
than the theoretical chemical timescale.
In this presentation, I will review what we have recently
understood and what we have not yet, on both aspects of
the same objects: the cold envelopes and the hot corinos
of solar type protostars.
