Mopra Observations of G305.2+0.2: Massive Star Formation at Different Evolutionary Stages?

Abstract

We have successfully used a new on-the-fly mapping technique with the Mopra radiotelescope to image G305.2+0.2 in transitions of 13CO, HCO+, N2H+, CH3CN and CH3OH. All these species appear to be concentrated towards the infrared-quiet methanol maser site G305A (G305.21+0.21). We suggest that this region contains an extremely deeply embedded site of massive star formation, with comparable qualities to the low mass Class 0 stage. The infrared-bright methanol maser site G305B (G305.21+0.20) also exhibits emission in all the mapped transitions, but always at a lower level. We suggest this is because it harbours a site of massive star formation older and more developed than G305.21+0.21. All transitions appear to be extended beyond the size of the Mopra beam (30"). 13CO and HCO+ line wings are suggestive of an outflow in the region, but the spatial resolution of these data is insufficient to identify the powering source. A narrow-lined (1.6 km/s compared to a typical line FWHM of 6.4 km/s) N2H+ source (G305SW) is found 90" to the south-west of the main star forming centres, which does not correspond to any CH3CN or CH3OH source, nor does it correspond well to 13CO or HCO+ emission in the vicinity. We suggest this may be a massive, cold, quiescent and possibly prestellar core.

7 pages, 5 figures

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Cited by in corpus (13)

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• Southern class I methanol masers at 36 and 44 GHz
• Chemistry in Infrared Dark Clouds
• A GLIMPSE-based search for 6.7-GHz Methanol Masers and the lifetime of their spectral features
• Physical and chemical conditions in methanol maser selected hot-cores and UCHII regions
• A Pilot Survey for the H${}_2$O Southern Galactic Plane Survey (HOPS)
• Parallaxes of 6.7-GHz Methanol Masers towards the G305.2 High-Mass Star Formation Region
• The G305 star forming complex: Wide-Area molecular mapping of NH3 and H2O masers
• The SOFIA Massive (SOMA) Star Formation Survey. II. High Luminosity Protostars
• G30.79~FIR~10: A gravitationally bound infalling high-Mass star forming clump
• Embedded Stellar Populations towards Young Massive Star Formation Regions I. G305.2+0.2
• A multi-scale exploration of a massive young stellar object - a transition disk around G305.20+0.21?
• Probing the magnetic fields of massive star forming regions with methanol maser polarisation