the molecular environments of massive star forming regions traced by class ii methanol masers

Nichol Cunningham

• Why?

• Massive stars are the building blocks of the universe.• Continuously chemically enrich our galaxy.

• Release massive amounts of energy.

•Where?

•Need to understand the initial processes of their formation.

•To do this must find earliest stages .•What are the initial conditions at the onset of

formation?•How?

•Need evolutionary indicators.•Use signposts of the earliest stages of formation.•Study the environments of these early signposts.

•Still sketchy and highly debated. • Defined as having mass

Problems •Begin burning hydrogen while still deeply embedded in natal cloud.

•Produce strong feedback effects such as:•Radiation pressure. •Photoionisation.

•Observationally difficult to study compared to low mass because:•Distant .•Rarer .•Form on short timescales.•Deeply enshrouded.•Form in dense clusters.

Microwave Amplification by the Stimulated Emission of Radiation

•Many species of masers.•Methanol Masers

•Class I collisionally excited•Class II radiatively pumped•6.7-GHz Methanol class II maser only traces young massive stars.

•Maser emission is non-thermal.•Can only exist under certain conditions, providing important information about their environments.

•Why?•Is found to be highly associated with young massive stars.•Believed to be created close to central protostellar object less than 10^3 AU•Could then use this emission to form a survey of young massive star formation

•Explore massive star forming regions traced by 6.7 class II methanol maser emission.

•Investigate the properties of their environments to try and understand their link as an evolutionary signpost.

•Investigate the link between class I and class II methanol maser emission.

•Determine if their environmental properties differ throughout the galaxy.

•Using a sample of 6.7-GHz masers from the MMB survey•Follow up observation from Parkes (64m) and Mopra (22m) single dish telescopes to explore the molecular environments.

PARKES

•Ammonia (1,1),(2,2),(3,3) and (4,4)

MOPRA

•CS (1 -0) 48.9-GHz transition•44-GHz class I methanol maser

Images taken from http://www.atnf.csiro.au/

267 Sources

Vlsr of MMB sources vs Vlsr of Mopra sources

70 per cent detection rate of class I sources

CS Linewidths of Sources With and Without Detected 44-GHz Class I Emission

Class I spectra of 44-GHz line taken from Pratap et al. 2008

•High mass star formation still remains unclear.

•Follow up higher spatial resolution molecular line surveys .

•(4,4) ammonia transition.

• ALMA!!

Image taken from: http://www.stfc.ac.uk/resources/image/jpg/alma.jpg