Complex Molecules in the Hot Core of the Low‐Mass Protostar NGC 1333 IRAS 4A

We report the detection of complex molecules (HCOOCH_3, HCOOH and CH_3CN),signposts of a "hot core" like region, toward the low mass, Class 0 sourceNGC1333-IRAS4A. This is the second low mass protostar where such complexmolecules have been searched for and reported, the other source beingIRAS16293-2422. It is therefore likely that compact (few tens of AUs) regionsof dense and warm gas, where the chemistry is dominated by the evaporation ofgrain mantles, and where complex molecules are found, are common in low massClass 0 sources.Given that the chemical formation timescale is much shorterthan the gas hot core crossing time, it is not clear whether the reportedcomplex molecules are formed on the grain surfaces (first generation molecules)or in the warm gas by reactions involving the evaporated mantle constituents(second generation molecules). We do not find evidence for large differences inthe molecular abundances, normalized to the formaldehyde abundance, between thetwo solar type protostars, suggesting perhaps a common origin.Comment: 13 pages, 3 figures; accepted by Ap