Context :

Aims : We investigate the origin of complex organic molecules ( COMs ) in the gas phase around the low-mass Class 0 protostar NGC1333-IRAS2A , to determine if the COM emission lines trace an embedded disk , shocks from the protostellar jet , or the warm inner parts of the protostellar envelope .

Methods : In the framework of the CALYPSO CALYPSO is the Continuum And Lines in Young ProtoStellar Objects survey . IRAM Plateau de Bure survey , we obtained large bandwidth spectra at sub-arcsecond resolution towards NGC 1333-IRAS2A .
We identify the emission lines towards the central protostar and perform Gaussian fits to constrain the size of the emitting region for each of these lines , tracing various physical conditions and scales .

Results : The emission of numerous COMs such as methanol , ethylene glycol , and methyl formate is spatially resolved by our observations .
This allows us to measure , for the first time , the size of the COM emission inside the protostellar envelope , finding that it originates from a region of radius 40–100 AU , centered on the NGC 1333-IRAS2A protostellar object .
Our analysis shows no preferential elongation of the COM emission along the jet axis , and therefore does not support the hypothesis that COM emission arises from shocked envelope material at the base of the jet .
Down to similar sizes , the dust continuum emission is well reproduced with a single power-law envelope model , and therefore does not favor the hypothesis that COM emission arises from the thermal sublimation of grains embedded in a circumstellar disk .
Finally , the typical scale \sim 60 AU observed for COM emission is consistent with the size of the inner envelope where T _ { dust } > 100 K is expected .
Our data therefore strongly suggest that the COM emission traces the hot corino in IRAS2A , i.e. , the warm inner envelope material where the icy mantles of dust grains evaporate because they are passively heated by the central protostellar object .

Conclusions :