2021ApJ...923..155M

We report the detection of more than 120 emission lines corresponding to eight complex organic molecules (COMs; CH₃OH, CH₃CH₂OH, CH₃OCH₃, CH₃OCHO, CH₃COCH₃, NH₂CHO, CH₂DCN, and CH₃CH₂CN) and three isotopologues (CH₂DOH, ¹³CH₃CN, and CH₃C¹⁵N) toward the western component of the Ser-emb 11 binary young stellar object using observations with the Atacama Large Millimeter/submillimeter Array at ∼1 mm. The complex organic emission was unresolved with a ∼0.''5 beam (∼220 au) in a compact region around the central protostar, and a population diagram analysis revealed excitation temperatures above 100 K for all COMs, indicating the presence of a hot corino. The estimated column densities were in the range of 10¹⁷-10¹⁸ cm^–2 for the O-bearing COMs, and three orders of magnitude lower for the N-bearing species. We also report the detection of H₂CO and CH₃OH emission in a nearby millimeter source that had not been previously cataloged. Ser-emb 11 is classified in the literature as a Class I source near the Class 0/I cutoff. The estimated COM relative abundances in Ser-emb 11 W and the other three Class I hot corino sources reported in the literature are consistent with those of Class 0 hot corinos, suggesting a continuity in the chemical composition of hot corinos during protostellar evolution.