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 isotopologs), most of which
are present in the cold and quiescent ambient cloud. Of particular interest
among the detected molecules 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, and
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 isotopologs 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 report the first detection in space of some minor isotopologs like
c-C3D. The exhaustive chemical characterization of L483 presented here,
together with similar studies of other prestellar and protostellar sources,
should allow us to identify the main factors that regulate the chemical
composition of cores along the process of formation of low-mass protostars.
