High mass star formation in the Southern hemisphere sky

1. High mass star formation in the Southern hemisphere sky Vincent Minier (Service d’Astrophysique, CEA Saclay), Michael Burton, Tracey Hill, Cormac Purcell, Steve Longmore, Andrew Walsh (UNSW, Sydney, Australia) In collaboration with: Mark Thompson (Hertfordshire), Maria Hunt (UNSW), Guido Garay (Universidad de Chile), F. Herpin, S. Bontemps(Obs. de Bordeaux), P. André, N. Peretto, F. Motte (SAp, CEA Saclay), Riccardo Cesaroni (Arcetri) Millimetre Workshop 2002, ATNF

2. High mass star formation in the Southern hemisphere sky Vincent Minier (CEA Saclay), Michael Burton, Tracey Hill, Cormac Purcell, Steve Longmore, Andrew Walsh (UNSW) Acknowledgements: French-Australian Science & Technology funding programme Embassy of France in Australia, MAE, MENESR DEST, Australian Government Department of Education, Science and Training Millimetre Workshop 2002, ATNF

3. High mass star formation (HMSF) • High mass stars: OB stars, > 8 M Key objects for galactic ecology & dynamics; • Radiative force vs. Gravitational force (York 1977): Frad/Fgrav=(L/4r2)/(GM/r2)  = 30 cm2 g-1 A star  Frad/Fgrav= 0.05 B star  Frad/Fgrav= 2.5 • Scenarios: collapse of a supersonically turbulent core (McKee & Tan 2003); accretion disk (Yorke 2003); coalescence (Bonnell et al. 2004).

4. High mass star formation Protostellar phases Observational constraints:  Cluster, far away (kpc)  confusion  Short lives (1-10 Myr)  rare  Still accreting  extinction (>20 mag) Cold to hot sources (20-200 K). Cluster 40” Proto-cluster NGC3603 Credit:Brandner et al. • MIR to mm, high angular resolution (< 1 arcsec)

5. ~ a few 104 – 106 yr ~ 104 – 10 5 yr Hot Core Phase Molecular Cloud Massive Star UC HII C HII  HII phase Cold Core Methanol Maser ~104 –a few104 yr 104 yr 105 yr 106 yr ? High mass star formation Protostellar phases Scientific questions:  Phases earlier than UC HII: collapse, accretion ?  Protostellar (« class 0 ») and prestellar cores?  Multiplicity, clustering mode ? mm + FIR + lines + MIR + NIR + radio + optical

6. Exploration of Southern high-mass star forming regions through methanol masers • Observed toward HMSF regions (Menten’91); • Maser conditions  HMSF density (107 cm-3) & Tdust (50- 150 K); • No maser toward low-mass star forming regions (Minier et al.’03). Southern hemisphere Pestalozzi, Minier & Booth, sub. Gal. Dist.=5 kpc molecular ring  Exclusive tracers

7. Multi-wavelength surveys of HMSF regions (Burton et al.) • Selection of methanol maser sites and UC HII regions (Walsh et al. ‘98, Thompson et al. ‘04)  131 fields • SIMBA/SEST 1.2 mm/continuum  detection of 403 warm dust clumps, cold clumps (Hill et al.); • SCUBA/JCMT 450/850 m cont. (Walsh et al.’03); • Mopra/ATNF 3 mm molecular lines (Purcell et al.); • High resolution: GEMINI (MIR), ATCA (1.2 cm & 3 mm cont/lines), VLBA (maser) & VLA (cm cont.) (Longmore et al., Minier et al.)

8. SIMBA results – dust emission 403 clumps toward 131 fields 250 mm-only clumps (no radio, no maser, no MSX) Distance: 0.3-16.7 kpc ; Mass: 5-37000 (av=1500) M Radius: 0.01 to 2.48 (av=0.5) pc ; Surface density: av=0.3 g cm-2 Density: 1.3x103 to 1.9x106 (av=8.4x104) cm-3 ; Av=10-500 mag (Hill, Burton, Minier et al. in prep.)

9. SIMBA results 403 clumps toward 131 fields 250 mm-only clumps (no radio, no maser, no MSX) nH2  r-2 Distance: 0.3-16.7 kpc ; Mass: 5-37000 (av=1500) M Radius: 0.01 to 2.48 (av=0.5) pc ; Surface density: av=0.3 g cm-2 Density: 1.3x103 to 1.9x106 (av=8.4x104) cm-3 ; Av=10-500 mag (Hill, Burton, Minier et al. in prep.)

10. mm MIR dark clouds Mm, masers, FIR not intense. Lsubmm/Ltotal  1%  Pre/protostellar FIR MIR bright HMPOs Mm, FIR, MIR Lsubmm/Ltotal  0.1%  Protoclusters MIR Clusters of UCHII Mm, cm, FIR, MIR, weak NIR Lsubmm/Ltotal  0.1% Minier et al. 2004 NIR

11. SPIRE & PACS • Need for Herschel SPIRE/PACS • 75-500 m SED maps; • Image clumps i.e. protoclusters; • SPIRE key project onStar Formation 30’’

12. Need for ALMA • Need subarcsec angular resolution: ; • Resolve clumps/protoclusters into cores and massive protostar multiple systems. 30’’ 104M pc-3 5’’ 2’’=5000 AU @ 2.5 kpc Cm cont. on NIR 104M pc-3 Cm cont. on MIR Submm Minier et al.’04, Longmore et al. in prep

13. 1.2-mm dust continuum towards HII region; Cooler clumps Example 1: NGC3576 (RCW57) Optical Image DSS SIMBA 1.2 mm continuum HII region + NIR clusters + masers Hill et al. in prep. • Reveals additional clumps along linear 'filament‘.

14. MSX 8-m data Cold clump ? Absorption = MIR dark clouds

15. Mopra - 13CO integrated map Cold clump

16. Mopra - HCO+ map Cold clump

17. Example 2: MIR dark cloud MIR dark, cold clump 1.2 mm overlaid on 8 m

18. Example 2: MIR dark cloud SED

19. Purcell et al. in prep. Cold massive protostellar clump ?

20. Conclusions • Identified a sample of 131 HMSF regions in the Galactic Plane; • 403 protoclusters: cold clumps (i.e. protostellar or prestellar), hot cores and UC HII regions; • Declinations from –65° to +23°, most regions being in the Southern hemisphere with –65° < dec < 0°; • Future work: imaging of « best » sources at higher angular resolution with ATCA at 12 and 3 mm, GEMINI in MIR (and perhaps VISIR, IRAM)  Preparation of a « key » project for ALMA