Lientjie de VilliersPhD Supervisor: Dr. M.A. Thompson

University of Hertfordshire

Methanol masers and the 6.7 GHz methanol maser surveyMolecular outflowsHARP instrument on the JCMTData reduction processResults:

outflow detection script3D representation and possible outflows3D overlay of different molecular emissons

Future work:Expand data from other surveys – Galactic planeMedical imaging analysis

Maser = Microwave Amplification by Stimulated Emission of RadiationTrace an IR bright stage immediately prior to development of UC HII regions1 ~ 104 year# molecules in quantum state 2 = n2

state 1 = n1 If n2/n1 > 1 population inversion due to radiative pumping MASER.

2 Classes2 :Class I – collisionally pumped, often associated with outflowsClass II - radiatively pumped – far IR emission by dust cocoon around the maser, uniquely associated with high mass star formation 3,4,5

Class II methanol masers: brightest radio sources in sky, & compact.Galaxy = transparent at 6.67 GHz ideal tracers for star formation in Galactic structure.

1 Codella et al. 2004; 2. Sobolev et al. 2005; 3. Sobolev et al. 1997; 4.Minier et al. 2003; 5. Ellingsen, 2005

Outflowing wind > vsound from protostar – accelerate surrounding molecular gas to vmg >> vcloud of quiescent cloud gas produce molecular outflow, a turbulent expanse of cloud gas from the vicinity of a stellar sourcePart of the SF process mass-loss phase during their protostellar stages 1

1 Arce et al. 2007

Search for outflows associated with methanol masers – the latter always associated with high mass SF its dynamic lifetime = upper bound on maser lifetimeDe Buizier (2009) observed the SiO (6-5) transition of 10 maser sources. Broad line wings indicate outflows all the sources with bright SiO lines, displayed broad line wings indicitave of outflow.

Not finally confirmed.

Heterodyne Array Receiver Program 16 pix heterodyne focal-plane array receiver

4x4 element array with SIS detectors

Beam size 14” @ 345 GHz

High 3D mapping speed

sensitivity at 325-375 GHz

Selection from a HARP-B outflow survey of 200 Class II methanol masers drawn from MMB catalogue of 6.7 GHz (4.49 cm) masers.13CO J=3-2 (trace outflows) C18O J=3-2 (see core)

Masers selected with wide range of luminosities, distances and galactic longitudes analyse differences in outflow properties.

Starlink’s NAMAKA version of the REDUCE SCIENCE PIPELINE

Raw timeseries image

~ Clip noisy ends~ Sub 1 baseline Bl. Subtracted

timeseries

Clumpfind baseline mask

3 baseline fit on timeseries

Pipeline reduced cube

~ Sub 3 baselline~ Makecube

Collapse along velocity axis – quality control

Collapsed image

~ Clip noisy ends~ Sub 1 baseline Bl. Subtracted

timeseries

Clumpfind baseline mask

3 baseline fit on timeseries

~ Sub 3 baselline~ Makecube

Collapsed along v over (peak-20km/s; peak+20 km/s)RA

Dec

Receptor #

Tim

e

Example: 13CO images from Maser source G30.704 -0.06

RA

Dec

CUBE COLLAPSED CUBEMore edge clippingDespikeRebin velocitySwitch of noisy receptors

Aim of this phase:

Simple outflow detection & contour mapping

3D image rendering with current astronomical software (GAIA) of both 13CO and C18O.

Detect outflows in 3D by eye

Create a 3D training set for future medical image analysis programs

Simple outflow detection method1:Using median filter: determine central v and width of source peakDerive from above: define BLUE = (-10 ; -2) GREEN = (-2; 2) RED = (2; 10)

1. Private communication: Antonio Chrysostomou – JAC, Hawaii

Simple outflow detection method1:Using median filter: determine central v and width of source peakDerive from above: define BLUE = (-10 ; -2) GREEN = (-2; 2) RED = (2; 10)Create 3 separate images by collapsing over above regions.

1. Private communication: Antonio Chrysostomou – JAC, Hawaii

Example: 13CO image from Maser source G30.760 -0.05

Example: 13CO image from Maser source G30.760 -0.05

3D rendering

in Gaia

3 separation between contours (receptor temp). Levels: 6.6 K; 4.3 K, 2.1 K

Blue: 13CO; Yellow: C18O; Plane: image plane located at central peak velocity

C18O : abundance thus opacity see core

13CO > abundant than C18O, see more structure like

outflows. Both molecules low enough density & low

opacity – trace dense gas in molecular cores where masers are embedded.

Another example of high velocity structures (possible outflows?)

Contours and 3D rendering of 13CO and C18O images of G24.790 +0.08

However, still inconclusive, need to be confirmed.

3 separation between contours (receptor temp). Levels: 6.1 K; 3.8 K, 1.5 K

Expand dataExpand current data set of 80 sources with 13CO and C18O maser observations from T. MooreGet 12CO images for all maser sources from 12CO galactic plane survey (JAC)

Investigate Medical Imaging optionsOutflows = irregular 3D shapes similarities with typical medical imaging problemsArce et al. (2010) visualized the molecular clouds from Perseus 3D in Ra-Dec-v space detected high velocity features (e.g. outflows)Used 3D Slicer from MIT Artificial Intelligence Lab & Surgical Planning Lab at Brighham and Women’s Hospital designed to help surgeons in image-guided surgery, diagnostics and brain research visualization.1

1. Borkin et al. 2005

“If the whole universe has no meaning, we should never have found out that it has no meaning: just as, if there were no light in the universe and therefore no creatures with eyes, we should never know it was dark. Dark would be without meaning.”

C.S. Lewis