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Lientjie de Villiers PhD Supervisor: Dr. M.A. Thompson University of Hertfordshire.

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Presentation on theme: "Lientjie de Villiers PhD Supervisor: Dr. M.A. Thompson University of Hertfordshire."— Presentation transcript:

1 Lientjie de Villiers PhD Supervisor: Dr. M.A. Thompson University of Hertfordshire

2 Methanol masers and the 6.7 GHz methanol maser survey Molecular outflows HARP instrument on the JCMT Data reduction process Results: outflow detection script 3D representation and possible outflows 3D overlay of different molecular emissons Future work: Expand data from other surveys – Galactic plane Medical imaging analysis

3 Maser = Microwave Amplification by Stimulated Emission of Radiation Trace an IR bright stage  immediately prior to development of UC HII regions 1 ~ 10 4 year # molecules in quantum state 2 = n 2 state 1 = n 1 I f n 2 /n 1 > 1  population inversion due to radiative pumping  MASER. 2 Classes 2 : Class I – collisionally pumped, often associated with outflows Class 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

4 Outflowing wind > v sound from protostar – accelerate surrounding molecular gas to v mg >> v cloud of quiescent cloud gas  produce molecular outflow, a turbulent expanse of cloud gas from the vicinity of a stellar source Part of the SF process  mass-loss phase during their protostellar stages 1 1 Arce et al Search for outflows associated with methanol masers – the latter always associated with high mass SF  its dynamic lifetime = upper bound on maser lifetime De 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.

5 Heterodyne Array Receiver Program  16 pix heterodyne focal-plane array receiver 4x4 element array with SIS detectors Beam size 345 GHz High 3D mapping speed  sensitivity at GHz

6 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. 13 CO J=3-2 (trace outflows) C 18 O J=3-2 (see core) Masers selected with wide range of luminosities, distances and galactic longitudes  analyse differences in outflow properties.

7 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

8 ~ 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 # Time Example: 13 CO images from Maser source G RA Dec CUBECOLLAPSED CUBE More edge clipping Despike Rebin velocity Switch of noisy receptors

9 Aim of this phase: Simple outflow detection & contour mapping 3D image rendering with current astronomical software (GAIA) of both 13 CO and C 18 O. Detect outflows in 3D by eye Create a 3D training set for future medical image analysis programs

10 Simple outflow detection method 1 : Using median filter: determine central v and width of source peak Derive  from above: define BLUE = (-10  ; -2  ) GREEN = (-2  ; 2  ) RED = (2  ; 10  ) 1. Private communication: Antonio Chrysostomou – JAC, Hawaii

11 Simple outflow detection method 1 : Using median filter: determine central v and width of source peak Derive  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: 13 CO image from Maser source G

12 3D rendering in Gaia 3  separation between contours (receptor temp). Levels: 6.6 K; 4.3 K, 2.1 K Blue: 13 CO; Yellow: C 18 O; Plane: image plane located at central peak velocity C 18 O :  abundance thus  opacity  see core 13 CO > abundant than C 18 O, see more structure like outflows. Both molecules low enough density & low opacity – trace dense gas in molecular cores where masers are embedded.

13 Another example of high velocity structures (possible outflows?) Contours and 3D rendering of 13 CO and C 18 O images of G However, still inconclusive, need to be confirmed. 3  separation between contours (receptor temp). Levels: 6.1 K; 3.8 K, 1.5 K

14 Expand data Expand current data set of  80 sources with 13 CO and C 18 O maser observations from T. Moore Get 12 CO images for all maser sources from 12 CO galactic plane survey (JAC)

15 Investigate Medical Imaging options Outflows = irregular 3D shapes  similarities with typical medical imaging problems Arce 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 Borkin et al. 2005

16 “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


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