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The Methanol Multibeam Survey: a unique window on high-mass star formation in our Galaxy

Published online by Cambridge University Press:  21 March 2013

J. L. Caswell
J. L. Caswell*
Affiliation:
CSIRO Astronomy and Space Science, ATNF, PO Box 76, Epping, NSW, Australia2121 email: [email protected]
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Abstract

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The Methanol Multibeam (MMB) survey has yielded over 1000 masers at the 6668-MHz methanol transition: a near-complete census throughout the Galactic disc, as evident from the discovery statistics, and corroborated by preliminary distance determinations. Each maser pinpoints a massive star in a brief early evolutionary phase. Follow-up comparisons reveal in most cases a matching IR source in the GLIMPSE survey. The methanol masers effectively distinguish the genuine high mass proto-stars from the many thousand IR mimics of similar color. Longer IR wavelength follow-ups by Herschel instruments, and in the radio mm-continuum, will refine the mass-range encompassed by the masers; and, complemented by radio measurements at short cm-wavelengths, will define the evolutionary stage of each site, distinguishing hyper-compact HII regions from an earlier phase. Follow-up studies of key molecular gas tracers, including closely associated masers (other methanol transitions, water and OH), reveal the extent of homogeneity in the population and environments of high mass stars.

Distance estimates based on the maser velocities have already allowed useful exploration of Galactic structure. Future astrometric parallax measurements extended to the full maser sample will precisely define the geometry of Galactic spiral arms of our Galaxy and independently define the velocity field, allowing a model-free study of Galactic rotation and dynamics. Associated OH masers (present at about half of the methanol sites) are being exploited to provide the first Galaxy-wide grid of ‘in situ’ magnetic field estimates.

Our detailed characterization of the Galactic methanol maser population provides a yardstick for extragalactic comparisons with M31 and the LMC. Notably, our survey of the LMC has shown its methanol maser population to be remarkably small relative to our Galaxy - a likely consequence of low LMC metallicity.

Keywords

masers — catalogs — Galaxy: structure — stars: formation — ISM: molecules
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S292: Molecular Gas, Dust, and Star Formation in Galaxies , August 2012 , pp. 79 - 82
Copyright
Copyright © International Astronomical Union 2013

References

Breen, S. L., Ellingsen, S. E., Caswell, J. L., & Lewis, B. E. 2010, MNRAS, 401, 2219CrossRefGoogle Scholar
Breen, S. L., Ellingsen, S. P., Caswell, J. L., et al. 2011, ApJ, 733, 80CrossRefGoogle Scholar
Breen, S. L., Ellingsen, S. P., Caswell, J. L., Green, J. A., et al. 2012a, MNRAS, 421, 1703Google Scholar
Breen, S. L., Ellingsen, S. P., Caswell, J. L., Green, J. A., et al. 2012b, MNRAS, in pressGoogle Scholar
Caswell, J. L., Fuller, G. A., Green, J. A.et al. 2010, MNRAS, 404, 1029CrossRefGoogle Scholar
Caswell, J. L., Fuller, G. A., Green, J. A.et al. 2011, MNRAS, 417, 1964CrossRefGoogle Scholar
Ellingsen, S. P., Breen, S. L., Sobolev, A. M., Voronkov, M. A., Caswell, J. L., & Lo, N. 2011, ApJ 742, 109CrossRefGoogle Scholar
Gallaway, M., Thompson, M. A., Lucas, P. W., Fuller, G. A., Caswell, J. L., et al. 2012, MNRAS, in pressGoogle Scholar
Green, J. A., Caswell, J. L., Fuller, G. A., et al. 2008, MNRAS, 385, 948CrossRefGoogle Scholar
Green, J. A., Caswell, J. L., Fuller, G. A., et al. 2009a, MNRAS, 392, 783CrossRefGoogle Scholar
Green, J. A., McClure-Griffiths, N. M., Caswell, J. L., et al. 2009b, ApJ, 696, L156CrossRefGoogle Scholar
Green, J. A., Caswell, J. L., Fuller, G. A., et al. 2010, MNRAS, 409, 913Google Scholar
Green, J. A., Caswell, J. L., McClure-Griffiths, N. M., et al. 2011, ApJ, 733, 27CrossRefGoogle Scholar
Green, J. A., Caswell, J. L., Fuller, G. A., et al. 2012a, MNRAS, 420, 3108CrossRefGoogle Scholar
Green, J. A., McClure-Griffiths, N. M., Caswell, J. L., Robishaw, T., & Harvey-Smith, L., 2012b, MNRAS, 425, 2530Google Scholar
Pestalozzi, M. R., Minier, V., & Booth, R. S. 2005, A&A, 432, 737Google Scholar
Pestalozzi, M. R., Chrysostomou, A., Collett, J. L., Minier, V., Conway, J., & Booth, R. S. 2007, A&A, 463, 1009Google Scholar
Reid, M. W., et al. 2009, ApJ, 700, 137CrossRefGoogle Scholar
Rygl, K. L. J., Brunthaler, A., Reid, M. J., et al. 2010, A&A, 511, A2Google Scholar
van der Walt, J. 2005, MNRAS, 360, 153Google Scholar
Voronkov, M. A., Caswell, J. L., Ellingsen, S. P., Breen, S. L., Britton, T. R., Green, J. A., Sobolev, A. M., & Walsh, A. J. 2012, in: Booth, R. S., Humphreys, E. M. L. & Vlemmings, W. H. T. (eds), Cosmic Masers from OH to H 0, Proc. IAU Symposium No. 287 (Cambridge: CUP), p. 433Google Scholar