Complex organic molecules in organic-poor massive young stellar objects

Abstract

Massive young stellar objects (MYSOs) with hot cores are classic sources of complex organic molecules. The origins of these molecules in such sources, as well as the small- and large-scale differentiation between nitrogen- and oxygen-bearing complex species, are poorly understood. We aim to use complex molecule abundances toward a chemically less explored class of MYSOs with weak hot organic emission lines to constrain the impact of hot molecular cores and initial ice conditions on the chemical composition toward MYSOs. We use the IRAM 30m and the Submillimeter Array to search for complex organic molecules over 8-16 GHz in the 1~mm atmospheric window toward three MYSOs with known ice abundances, but without luminous molecular hot cores. Complex molecules are detected toward all three sources at comparable abundances with respect to CH${}_3$OH to classical hot core sources. The relative importance of CH${}_3$CHO, CH${}_3$CCH, CH${}_3$OCH${}_3$, CH${}_3$CN, and HNCO differ between the organic-poor MYSOs and hot cores, however. Furthermore, the N-bearing molecules are generally concentrated toward the source centers, while most O- and C-bearing molecules are present both in the center and in the colder envelope. Gas-phase HNCO/CH${}_3$OH ratios are tentatively correlated with the ratios of NH${}_3$ ice over CH${}_3$OH ice in the same lines of sight, which is consistent with new gas-grain model predictions. Hot cores are not required to form complex organic molecules, and source temperature and initial ice composition both seem to affect complex organic distributions toward MYSOs. To quantify the relative impact of temperature and initial conditions requires, however, a larger spatially resolved survey of MYSOs with ice detections.

Accepted for publication by A&A, 28 pages in referee format, 12 figures

References in corpus (20)

• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• Formation rates of complex organics in UV irradiated CH3OH-rich ices I: Experiments
• A three-phase chemical model of hot cores: the formation of glycine
• Testing grain-surface chemistry in massive hot-core regions
• Evaporation of ices near massive stars: models based on laboratory TPD data
• A cold complex chemistry toward the low-mass protostar B1-b: evidence for complex molecule production in ices
• The Physical and Chemical Structure of Hot Molecular Cores
• Microscopic simulation of methanol and formaldehyde ice formation in cold dense cores
• Chemistry as a probe of the structures and evolution of massive star forming regions
• A quantitative analysis of OCN- formation in interstellar ice analogs
• Hot gas and dust in a protostellar cluster near W3(OH
• Water in massive star-forming regions: HIFI observations of W3 IRS5
• Subarcsecond mid-infrared and radio observations of the W3 IRS5 protocluster
• Chemistry of massive young stellar objects with a disk-like structure
• Millimeter interferometry of W3 IRS5: A Trapezium in the making
• Hubble Space Telescope NICMOS Imaging of W3 IRS 5: A Trapezium in the Making?
• Detection of a hot core in the intermediate-mass (IM) Class 0 protostar NGC 7129--FIRS2
• The Spatial Distribution of Organics toward the High-Mass YSO NGC 7538 IRS9
• A rotating disk around the very young massive star AFGL 490
• Protostars and Outflows in the NGC7538 - IRS9 Cloud Core

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