On the origin of C${}_4$H and CH${}_3$OH in protostellar envelopes

Abstract

The formation pathways of different types of organic molecules in protostellar envelopes and other regions of star formation are subjects of intense current interest. We here present observations of C${}_4$H and CH${}_3$OH, tracing two distinct groups of interstellar organic molecules, toward 16 protostars in the Ophiuchus and Corona Australis molecular clouds. Together with observations in the literature, we present C${}_4$H and CH${}_3$OH data from single-dish observations of 40 embedded protostars. We find no correlation between the C${}_4$H and CH${}_3$OH column densities in this large sample. Based on this lack of correlation, a difference in line profiles between C${}_4$H and CH${}_3$OH, and previous interferometric observations of similar sources, we propose that the emission from these two molecules is spatially separated, with the CH${}_3$OH tracing gas that has been transiently heated to high ($\sim$70-100 K) temperatures, and the C${}_4$H tracing the cooler large-scale envelope where CH${}_4$ molecules have been liberated from ices. These results provide insight in the differentiation between hot corino and warm carbon-chain chemistry in embedded protostars.

7 pages, 2 figures, accepted for publication in ApJL

References in corpus (7)

• The Evolution of Outflow-Envelope Interactions in Low-Mass Protostars
• Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II
• Modeling the Lukewarm Corino Phase - is L1527 unique?
• Structure and dynamics of the class I young stellar object L1489 IRS
• Complex organic molecules during low-mass star formation: Pilot survey results
• Strong irradiation of protostellar cores in Corona Australis
• Water around IRAS15398-3359 observed with ALMA

Cited by in corpus (8)

• Externally heated protostellar cores in the Ophiuchus star-forming region
• The connection between warm carbon chain chemistry and interstellar irradiation of star-forming cores
• FAUST VII. Detection of A Hot Corino in the Prototypical Warm Carbon-Chain Chemistry Source IRAS 15398-3359
• FAUST VI. VLA 1623--2417 B: a new laboratory for astrochemistry around protostars on 50 au scale
• Modelling carbon-chain species formation in lukewarm corinos with new multi-phase models
• Chemical compositions in the vicinity of protostars in Ophiuchus
• Parsec scales of carbon chain and complex organic molecules in AFGL 2591 and IRAS 20126
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO