INTERMEDIATE-MASS HOT CORES AT ∼500 AU: DISKS OR OUTFLOWS?

Observations with the Plateau de Bure Interferometer in the most extended configuration toward two intermediate-mass star-forming regions, IRAS 22198+6336 and AFGL 5142, reveal the presence of several complex organic molecules at similar to 500 AU scales, confirming the presence of hot cores in both regions. The hot cores are not rich in CN-bearing molecules, as often seen in massive hot cores, and are mainly traced by CH3CH2OH, (CH2OH)(2), CH3COCH3, and CH3OH, with, additionally, CH3CHO, CH3OD, and HCOOD for IRAS 22198+6336, and C6H and (OCS)-C-13 for AFGL 5142. The emission of complex molecules is resolved down to sizes of similar to 300 and similar to 600 AU, for IRAS 22198+6336 and AFGL 5142, respectively, and most likely is tracing protostellar disks rather than flattened envelopes or toroids as is usually found. This is especially clear for the case of IRAS 22198+6336, where we detect a velocity gradient for all the mapped molecules perpendicular to the most chemically rich outflow of the region, yielding a dynamic mass less than or similar to 4 M-circle dot. As for AFGL 5142, the hot core emission is resolved into two elongated cores separated similar to 1800 AU. A detailed comparison of the complex molecule peaks to the new CO (2-1) data and H2O maser data from the literature suggests also that for AFGL 5142 the complex molecules are mainly associated with disks, except for a faint and extended molecular emission found to the west, which is possibly produced in the interface between one of the outflows and the dense surrounding gas.