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Massive Young Stars in the Galaxy Melvin Hoare University of Leeds UK.

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Presentation on theme: "Massive Young Stars in the Galaxy Melvin Hoare University of Leeds UK."— Presentation transcript:

1 Massive Young Stars in the Galaxy Melvin Hoare University of Leeds UK

2 Outline Introduction –Massive YSOs High resolution observations The RMS Survey –Galaxy-wide survey for massive YSOs Next generation galactic plane surveys –UKIDSS GPS, SCUBA2, CORNISH Conclusions

3 Massive Star Formation What determines the upper IMF? –The physics of infall Turbulence? Magnetic fields? Dynamics? –The physics of outflow Radiation pressure on dust? Radiation pressure on gas? MHD driven flows?

4 Massive Young Stellar Objects Luminous (>10 4 L ), embedded IR source Bipolar molecular outflow Often has associated maser emission Compact, ionised wind (v~100 km s -1 )

5 Evolutionary Outline Hot Core YSO UCHII OB Star SED: Sub-mm Mid-IR Near-IR Visual Masers: CH 3 OH H 2 O OH Radio: No radio Weak Radio Strong Radio

6 High Resolution Observations OVRO: 2.7mm 2 " CO 4 " S140 IRS 1

7 VLA 5 GHz (1.4 GHz)

8 VLA 8 GHz Tofani et al. (1995)

9 MERLIN 5 GHz 0.1" 2 m speckle 0.2"

10 - Monopolar reflection nebula in a massive YSO - Scattered light in blueshifted outflow lobe - Polarimetry confirms scattered nature of extended emission S140 IRS 1 Schertl et al (2000)

11 Radio Proper Motions 5 year baseline1 month baseline

12 Mid-IR Diffraction-Limited Imaging S140 IRS 1, 2 & 3 - Subaru 24.5 m, 0.6 resolution - Fujiyoshi, Hoare, Moore

13 GL 989Standard Star 24.5 m images

14 Azimuthally-averaged profiles 24.5 m10.5 m

15 Resolution of warm dust emission Models with r -2, r -1.5, r -1, r -0.5 density distribution Observations support steep density gradient

16 Mm Interferomety Resolution of the cool dust continuum emission from the envelope ATCA mm interferometer 5 x 22m dishes and 128 MHz bandwidth Hoare, Urquhart, Gibb, in prep

17 MYSO Samples Well characterised MYSOs number in the tens Not systematically found and mostly nearby May not be representative Need well-selected sample that number in the hundreds Can then study properties in a statistically robust way

18 Surveys for MYSOs Too obscured in near-IR Radio continuum too weak No single maser transition always present Molecular cores do not necessarily contain YSOs Need to use IR where bulk of energy emerges IRAS-based searches suffer from confusion

19 The MSX Galactic Plane Survey 8, 12, 14 and 21 m, 18 resolution, |b|<5 o IRAS 12 mMSX 8 mMSX 21 m W75 N Region

20 The Red MSX Source (RMS) Survey Colour-select massive YSO candidates from the MSX Point Source Catalogue and 2MASS near-IR survey Delivers ~2000 candidates Many other object types with similar near- and mid-IR colours

21 + OH/IR stars + C stars+ UCHII regions + PN Massive YSOs

22 Multi-wavelength Ground-based Follow-up Campaign Identify and eliminate confusing sources Begin characterisation of the massive YSOs RMS Team: –Stuart Lumsden, Rene Oudmaijer, James Urquhart, Ant Busfield, Tamara King, Andrew Clarke (Leeds, UK) –Toby Moore, James Allsopp (Liverpool JMU, UK) –Cormac Purcell, Michael Burton (UNSW, Australia) –Zhibo Jiang, Wang Min (PMO, China)

23 Radio Continuum 5 GHz, 1 resolution at VLA & ATCA 1700 objects observed so far Compact H II RegionMassive YSO candidate

24 Kinematic Distances 13 CO at Mopra, Onsala, JCMT, PMO & GRS 1700 targets observed

25 Galactic Distribution

26 Resolving Distance Ambiguities with H I

27 Mid-IR 10 m, 0.8 resolution at UKIRT and ESO 3.6m, 350 objects observed + GLIMPSE

28 Near-IR K-band imaging at UKIRT & ANU 2.3m + 2MASS 400 targets observed H+K band spectroscopy at UKIRT 120 targets observed


30 Next Generation Plane Surveys Deeper and higher spatial resolution Complete wavelength coverage Common areas Matched sensitivities and resolutions The Spitzer 4-8 m GLIMPSE legacy survey is the starting point (10 o <l<65 o, |b|<1 o )


32 Proposed VLA Survey CORNISH Project (Hoare, Diamond, Churchwell, Kurtz, …) –CO-ordinated Radio N Infrared Survey for High-mass star formation 5 GHz, 1 resolution B configuration VLA survey of the northern GLIMPSE region 9000 pointings of 2 minutes each requiring 400 hours in total 2 mJy 50% completeness limit

33 CORNISH Science Unbiased census of UCHII regions –Triggering and clustering of massive star formation Identification of radio loud/quiet objects found in GLIMPSE –UCHII regions/Massive YSOs –PN/Proto-PN Be stars, WR stars, active binaries, X-ray sources etc. Legacy science

34 H II region MYSO

35 Conclusions High resolution observations are beginning to resolve the envelope and winds The RMS survey will deliver ~1000 massive YSOs over the whole galaxy GLIMPSE, in combination with other surveys, will deliver very large numbers of intermediate mass YSOs right across the inner galaxy.

36 Large well-selected samples for future high resolution studies e.g. 8m, ALMA, SKA The combination of GLIMPSE and UKIDSS GPS will be particularly powerful for YSO, evolved star and stellar population studies Future SCUBA2, HERSCHEL and CORNISH surveys will be excellent tools for systematic massive star formation studies

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