The mid-infrared environments of 6.7 GHz Methanol Masers from the Methanol Multi-Beam Survey

Abstract

We present a study of the mid-infrared environments and association with star formation tracers of 6.7 GHz methanol masers taken from the Methanol Multi-Beam (MMB) Survey. Our ultimate goal is to establish the mass of the host star and its evolutionary stage for each maser site. As a first step, the GLIMPSE survey of the Galactic Plane is utilised to investigate the environment of 776 methanol masers and we find that while the majority of the masers are associated with mid-infrared counterparts, a significant fraction (17%) are not associated with any detectable mid-infrared emission. A number of the maser counterparts are clearly extended with respect to the GLIMPSE point spread function and we implement an adaptive non-circular aperture photometry (ANCAP) technique to determine the fluxes of the maser counterparts. The ANCAP technique doubles the number of masers with flux information at all four wavelengths compared to the number of the corresponding counterparts obtained from the GLIMPSE Point Source Catalogue. The colours of the maser counterparts are found to be very similar to the smaller study carried out by Ellingsen (2006). The MMB masers are weakly associated with Extended Green Objects (EGOs) and Red MSX Survey (RMS) embedded sources (YSO and HII classifications) with 18% and 12% of masers associated with these objects respectively. The majority of MMB masers (60%) have detectable GLIMPSE infrared counterparts but have not been identified with previously recognised tracers of massive star formation; this confirms that the MMB survey has the potential to identify massive star forming regions independent of infrared selection.

14 pages, 11 figures. Some figures reduced in resolution for this version. Accepted by MNRAS. Note: Table 1 will be available in its entirety upon publication of the article in MNRAS

References in corpus (14)

• The UKIDSS Galactic Plane Survey
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• A Class I and Class II Methanol Maser Survey of Extended Green Objects (EGOs) from the GLIMPSE Survey
• Intrinsically Red Sources observed by Spitzer in the Galactic Mid-Plane
• A systematic survey for infrared star clusters with |b|<20deg using 2MASS
• The 6-GHz Multibeam Maser Survey I. Techniques
• The 6-GHz methanol multibeam maser catalogue IV: Galactic longitudes 186 to 330 including the Orion-Monoceros region
• Multi-wavelength observations of Southern Hot Molecular Cores traced by methanol masers - I. Ammonia and 24 GHz Continuum Data
• The RMS Survey: Mid-Infrared Observations of Candidate Massive YSOs in the Southern Hemisphere
• A GLIMPSE-based search for 6.7-GHz Methanol Masers and the lifetime of their spectral features
• 12.2-GHz methanol maser MMB follow-up catalogue - I. Longitude range 330 to 10 degrees
• Absolute diffuse calibration of IRAC through mid-infrared and radio study of HII regions
• 37 GHz methanol masers : Horsemen of the Apocalypse for the class II methanol maser phase?
• A general catalogue of 6.7GHz methanol masers II: statistical analysis

Cited by in corpus (11)

• The Red MSX Source Survey: the Massive Young Stellar Population of our Galaxy
• ATLASGAL --- properties of compact HII regions and their natal clumps
• Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions
• ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum Characterization of an Evolutionary Sample
• Surveys of Clumps, Cores, and Condensations in Cygnus X: I. a New Catalog of ~0.1 pc Massive Dense Cores
• 12.2-GHz methanol maser MMB follow-up catalogue - I. Longitude range 330 to 10 degrees
• High-mass Starless Clumps in the inner Galactic Plane: the Sample and Dust Properties
• A search for water masers associated with class II methanol masers - II. Longitude range 341${}^{\circ }$ to 6${}^{\circ }$
• A search for water masers associated with class II methanol masers - I. Longitude range 6 to 20 degrees
• 12.2-GHz methanol maser MMB follow-up catalogue - III. Longitude range 10 to 20 degrees
• The Evolutionary Status of Protostellar Clumps Hosting Class II Methanol Masers