Hot corino chemistry in the Class I binary source Ser-emb 11

TL;DR

This study reports the detection of complex organic molecules in the hot corino region of the Class I binary protostar Ser-emb 11, revealing chemical similarities with earlier-stage Class 0 hot corinos and providing insights into chemical evolution during star formation.

Contribution

First detection of over 120 emission lines of complex organic molecules in Ser-emb 11, demonstrating the presence of a hot corino in a Class I source and comparing its chemistry with younger protostars.

Findings

Detected over 120 emission lines of complex organic molecules.

Found excitation temperatures above 100 K indicating a hot corino.

Chemical abundances are consistent with those in Class 0 hot corinos.

Abstract

We report the detection of more than 120 emission lines corresponding to 8 complex organic molecules (CH3OH, CH3CH2OH, CH3OCH3, CH3OCHO, CH3COCH3, NH2CHO, CH2DCN, and CH3CH2CN) and 3 isotopologues (CH2DOH, 13CH3CN, and CH3C15N) toward the western component of the Ser-emb 11 binary young stellar object (YSO) 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 10^17 - 10^18 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 catalogued. 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.