The Two Hot Corinos of the SVS13-A Protostellar Binary System: Counterposed Siblings
Résumé
We present ALMA high-angular-resolution (~50 au) observations of the Class I binary system SVS13-A. We report images of SVS13-A in numerous interstellar complex organic molecules: CH3OH, 13CH3OH, CH3CHO, CH3OCH3, and NH2CHO. Two hot corinos at different velocities are imaged in VLA4A (V sys = +7.7 km s-1) and VLA4B (V sys = +8.5 km s-1). From a non-LTE analysis of methanol lines, we derive a gas density of 3 × 108 cm-3 and gas temperatures of 140 and 170 K for VLA4A and VLA4B, respectively. For the other species, the column densities are derived from an LTE analysis. Formamide, which is the only N-bearing species detected in our observations, is more prominent around VLA4A, while dimethyl ether, methanol, and acetaldehyde are associated with both VLA4A and VLA4B. We derive in the two hot corinos abundance ratios of ~1 for CH3OH, 13CH3OH, and CH3OCH3; ~2 for CH3CHO; and ~4 for NH2CHO. The present data set supports chemical segregation between the different species inside the binary system. The emerging picture is that of an onion-like structure of the two SVS13-A hot corinos, caused by the different binding energies of the species, also supported by ad hoc quantum chemistry calculations. In addition, the comparison between molecular and dust maps suggests that the interstellar complex organic molecules emission originates from slow shocks produced by accretion streamers impacting the VLA4A and VLA4B disks and enriching the gas-phase component.
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