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107/108 GHz methanol masers with ALMA

107/108 GHz methanol masers with ALMA. Simon Ellingsen University of Tasmania. Methanol masers – what and where. Methanol masers are empirically divided into two groups:

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107/108 GHz methanol masers with ALMA

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  1. 107/108 GHz methanol masers with ALMA Simon Ellingsen University of Tasmania

  2. Methanol masers – what and where • Methanol masers are empirically divided into two groups: • Class I masers are associated with outflows and low velocity shocks, they are collisionally pumped. Strong transitions at 36, 44, 95, 229 GHz. • Class II masers are exclusively associated with the environment close to very young high-mass stars, they are radiatively pumped. Strong transitions at 6, 12, 107 GHz. • You frequently find class I and II methanol masers associated with the same object, but not coincident. • Often multiple class II (or class I) methanol transitions are observed to be coincident spatially and in velocity. 107 GHz methanol masers with ALMA

  3. + = 6.7 GHz methanol masers + = OH masers + = water masers Green contours = 95 GHz methanol Black contours = 3cm continuum. Blue = 3.6 μm Green = 4.5 μm Red = 8.0 μm Great Barriers in High-Mass Star Formation 13-17 September 2010

  4. Methanol masers - Science • What can you do with multiple coincident maser transitions? • Determine the physical conditions at very high resolution, by modeling the observed ratio of the different transitions. • Utilize the presence/absence of different transitions as an evolutionary clock. 107 GHz methanol masers with ALMA

  5. Methanol Maser pumping models Cragg et al. (2005) Great Barriers in High-Mass Star Formation 13-17 September 2010

  6. Methanol masers - Science EGOs water • What can you do with multiple coincident maser transitions? • Determine the physical conditions at very high resolution, by modeling the observed ratio of the different transitions. • Utilize the presence/absence of different transitions as an evolutionary clock. OH class II methanol 6.7 GHz 12.2 GHz UCHII class I methanol Relative lifetime (x 104 years) 0 1 2 3 4 5 107 GHz methanol masers with ALMA

  7. Methanol masers in A+ rotational subspecies : Class I Class II Figure courtesy of Maxim Voronkov. 107 GHz methanol masers with ALMA

  8. Low-hanging fruit • The 107 GHz (31-40 A+) methanol masers are direct analogues of the 6.7 GHz (51-60 A+). • Approximately 25 107 GHz masers have been detected in previous single-dish searches (e.g. Caswell et al. 2000). • These look like ideal targets for cycle 0 science : • Intense • Compact • Low frequency Caswell et al. (2000) 107 GHz methanol masers with ALMA

  9. Class I masers • There are a number of relatively strong and common class I transitions in band 3 (84 GHz and 95 GHz). • Also the 229 GHz transition falls within band 6. • These are more spatially distributed and may be better targets for later cycles. 107 GHz methanol masers with ALMA

  10. Conclusions • ALMA observations of 107 GHz methanol will allow us to • Constrain the physical conditions in the masing regions. • Constrain evolutionary maser-based clocks. • - “close the loop” on the class II methanol masers. 107 GHz methanol masers with ALMA

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