A multi-transition molecular line study of candidate massive young stellar objects associated with methanol masers

Abstract

We characterize the molecular environment of candidate massive young stellar objects (MYSOs) signposted by methanol masers. Single pixel observations of 10 transitions of HCO^+, CO and CS isotopomers were carried out, using the IRAM 30m telescope. We studied a sample of 28 targets for which the 6.7GHz maser emission positions are known with a sub-arcsecond accuracy. The systemic velocity inferred from the optically thin lines agrees within 3km/s with the central velocity of the maser emission for most of the sources. About 64% of the sources show line wings in one or more transitions of CO, HCO^+ and CS species, indicating the presence of molecular outflows. Comparison of the widths of line wings and methanol maser emission suggests that the 6.7GHz maser line traces the environment of MYSO of various kinematic regimes. Therefore conditions conducive for the methanol maser can exist in the inner parts of molecular clouds or circumstellar discs as well as in the outer parts associated with molecular outflows. Calculations of the physical conditions based on the CO and HCO^+ lines and the CS line intensity ratios refine the input parameters for maser models.

9 pages, 4 figures, accepted in A&A

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Cited by in corpus (31)

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• Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions
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• Major structures of the inner Galaxy delineated by 6.7-GHz methanol masers
• A Search for Infall Evidence in EGOs I: the Northern Sample
• Statistical properties of 12.2 GHz methanol masers associated with a complete sample of 6.7 GHz methanol masers
• Absolute positions of 6.7-GHz methanol masers
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• The Arecibo Methanol Maser Galactic Plane Survey - III: Distances and Luminosities
• Parkes full polarization spectra of OH masers - I. Galactic longitudes 350 through the Galactic Centre to 41
• 12.2-GHz methanol maser MMB follow-up catalogue - II. Longitude range 186 to 330 degrees
• A search for water masers associated with class II methanol masers - II. Longitude range 341${}^{\circ }$ to 6${}^{\circ }$
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• Continuity of accretion from clumps to Class 0 high-mass protostars in SDC335
• MALT-45: A 7mm survey of the southern Galaxy - II. ATCA follow-up observations of 44GHz class I methanol masers
• VLA observations of water masers towards 6.7 GHz methanol maser sources
• The 6-GHz multibeam maser survey III: comparison between the MMB and HOPS
• Ion and neutral molecules in the W43-MM1(G30.79 FIR 10) infalling clump
• Analysis and test of the central-blue-spot infall hallmark
• Discovery of four water masers in the Small Magellanic Cloud
• Orientation effect on the ligh curve shape of periodic methanol maser sources
• Study of the dense molecular gas surrounding the "Extended Green Object" G35.03+0.35
• Milliarcsecond structure of water maser emission in two young high-mass stellar objects associated with methanol masers
• Searching for Molecular Jets from High-Mass Protostars
• Mid-Infrared and Maser Flux Variability Correlation in Massive Young Stellar Object G036.70+00.09
• Detections of Compact Radio Continuum toward Methanol Maser Rings Using the VLA