Spitzer mid-IR image of the DR21 region in the Cygnus-X molecular complex Image Credit: NASA, Spitzer Space Telescope.

 To test our best models of methanol masers  To observe massive star formation at its earliest stages

Energy Levels of E-methanol (Cragg et al, 2005). J, K rotational quantum numbers, v t and v CO vibrational 6.7GHz transition is the first astrophysical methanol maser to switch on in massive star-forming regions: 5 1 – 6 0 A + Notation: J K – J’ K’ A sgn(p) Energy levels of A- methanol, with decay paths to astrophysical maser population inversions illustrated with arrows. (Cragg et al, 1992).

 Not strongly dependent on gas temperature, pumped by radiation from dust  Sharp switch on at ~110 K dust temperature, and after that, not strongly dependent  Switch off over 10 8 cm -3 gas number density due to thermal quenching  Amplification along line of sight for specific column density cm -3 s.

Left: MAMBO contour map of DR21 Right: MAMBO contour map with 8μm map overlaid Image Credit: Motte et al, Cygnus-X is a giant molecular complex in the Cygnus constellation, a star forming region with about 13 times the mass of the Orion nebula. DR21 is a cloud in the north of Cygnus-X in which we found masers. We selected targets identified by stellar signposts such as SiO outflows in Motte et al, 2007.

 M ulti- E lement R adio L inked I nterferometer N etwork  Mark II (Jodrell Bank, pictured), Cambridge, Defford, Knockin, Darnhall, Pickmere Image Credit: Jodrell Bank Observatory. 217 km

Pictured: Spectrum of DR21-N53 centred on 6.668GHz, produced with AIPS. Calibration: Bandpass to correct for differences in sensitivity across the spectrum. Amplitude and phase calibrations for varying conditions and forming the image. Split peak corresponding to a single maser Single peak corresponding to a different maser Singlet and doublet as yet not located

 Two known masers confirmed and one to three distinct new masers discovered  Null results on other targets: why?  Gas density sufficient in all targets: must be temperature  Masers were detected in massive cores with strong SiO outflows from their poles, as measured by ∫T SiO dv.

SiO outflows from the poles were an indicator of stellar activity we used to select our targets. Left: spectra of the six strongest SiO outflows. Two to four of the targets to the left have methanol masers, and no others in the sample of 17. N12 and N40 have much lower mass than the maser candidates. Hypothesis: only those protostellar cores with the strongest SiO outflows have methanol masers. Image Credit: Motte et al, Maser Maser? No Maser Brightness temperature (K) Velocity (kms -1 )

 Improve phase calibration and image the masers, i.e. are they in disks?  Map velocity distribution in the masers: what are the characteristics of the disk?  Confirm SiO – methanol correlation with larger samples and greater sensitivity  Extend to mid-IR sources

Thank you to Dr Lisa Harvey-Smith for her encouragement, ideas, endless debugging and giving me the opportunity to do the project in the first place!