A sensitive 3 mm line survey of L483: a broad view of the chemical composition of a core around a Class 0 object

We present an IRAM 30m line survey of the dense core L483 in the 3 mm band. We detected 71 molecules (140 including different isotopologues), most of which are present in the cold and quiescent ambient cloud. Of particular interest are the cis isomer of HCOOH, the complex organic molecules HCOOCH3, CH3OCH3, and C2H5OH, a wide variety of carbon chains, nitrogen oxides like N2O, and saturated molecules like CH3SH. In general, fractional molecular abundances in L483 are systematically lower than in TMC-1 (especially for carbon chains), tend to be higher than in L1544 and B1-b, while they are similar to those in L1527. Apart from the overabundance of carbon chains in TMC-1, we find that L483 does not have a marked chemical differentiation with respect to starless/prestellar cores like TMC-1 and L1544, although it does chemically differentiate from Class 0 hot corino sources like IRAS 16293-2422. This fact suggests that the chemical composition of the ambient cloud of some Class 0 sources could be largely inherited from the dark cloud starless/prestellar phase. We also derived isotopic ratios for a variety of molecules, some of which show isotopic anomalies like an extreme depletion in 13C for one of the two isotopologues of c-C3H2, a drastic enrichment in 18O for SO and HNCO (SO being also largely enriched in 17O), and different abundances for the two 13C substituted species of C2H and the two 15N substituted species of N2H+. We quantify for the first time the deuterium fractionation for HDCCO and c-C3D. The detailed chemical characterization of the dense core L483 presented here provides a piece, that together with similar exhaustive characterizations of other low-mass prestellar and protostellar sources, should allow us to understand which are the main factors that regulate the chemical composition of cores along the process of formation of low-mass protostars.