Discovery of a Hot Corino in the Bok Globule B335

TL;DR

This paper presents the first evidence of a hot corino in a Bok globule, detected via ALMA observations of complex organic molecules around a low-mass protostar, indicating a compact, warm chemical environment similar to known hot-corino sources.

Contribution

It reports the discovery of a hot corino in B335, expanding the understanding of hot corino environments to Bok globules and providing detailed molecular detections with ALMA.

Findings

Detection of saturated complex organic molecules in a compact region around the protostar.

Presence of both extended and compact sulfur-bearing molecules.

Fractional abundances of COMs comparable to known hot-corino sources.

Abstract

We report the first evidence of a hot corino in a Bok globule. This is based on the ALMA observations in the 1.2 mm band toward the low-mass Class 0 protostar IRAS 19347+0727 in B335. Saturated complex organic molecules (COMs), CH$_3$CHO, HCOOCH$_3$, and NH$_2$CHO, are detected in a compact region within a few 10 au around the protostar. Additionally, CH$_3$OCH$_3$, C$_2$H$_5$OH, C$_2$H$_5$CN, and CH$_3$COCH$_3$ are tentatively detected. Carbon-chain related molecules, CCH and c-C$_3$H$_2$, are also found in this source, whose distributions are extended over a few 100 au scale. On the other hand, sulfur-bearing molecules CS, SO, and SO$_2$, have both compact and extended components. Fractional abundances of the COMs relative to H$_2$ are found to be comparable to those in known hot-corino sources. Though the COMs lines are as broad as 5-8 km s$^{-1}$, they do not show obvious rotation motion in the present observation. Thus, the COMs mainly exist in a structure whose distribution is much smaller than the synthesized beam (0."58 x 0."52).