21 November 2002Millimetre Workshop 2002, ATNF 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)

21 November 2002Millimetre Workshop 2002, ATNF 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

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): F rad /F grav =(  L/4  r 2 )/(GM/r 2 )  = 30 cm 2 g -1 A star  F rad /F grav = 0.05 B star  F rad /F grav = 2.5 Scenarios: collapse of a supersonically turbulent core (McKee & Tan 2003); accretion disk (Yorke 2003); coalescence (Bonnell et al. 2004).

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

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 ~ a few 10 4 – 10 6 yr Hot Core Phase UC H II  C H II  H II phase Methanol Maser ~ 10 4 – 10 5 yr ~10 4 – a few 10 4 yr Cold Core Molecular Cloud 10 4 yr10 5 yr10 6 yr Massive Star ?

Southern hemisphere Gal. Dist.=5 kpc  molecular ring Exploration of Southern high-mass star forming regions through methanol masers Pestalozzi, Minier & Booth, sub. Observed toward HMSF regions (Menten’91); Maser conditions  HMSF density (10 7 cm -3 ) & T dust ( K); No maser toward low-mass star forming regions (Minier et al.’03).  Exclusive tracers

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.)

SIMBA results – dust emission Distance: kpc ; Mass: (av=1500) M  Radius: 0.01 to 2.48 (av=0.5) pc ; Surface density: av=0.3 g cm -2 Density: 1.3x10 3 to 1.9x10 6 (av=8.4x10 4 ) cm -3 ; Av= mag (Hill, Burton, Minier et al. in prep.) 403 clumps toward 131 fields 250 mm-only clumps (no radio, no maser, no MSX)

SIMBA results Distance: kpc ; Mass: (av=1500) M  Radius: 0.01 to 2.48 (av=0.5) pc ; Surface density: av=0.3 g cm -2 Density: 1.3x10 3 to 1.9x10 6 (av=8.4x10 4 ) cm -3 ; Av= mag (Hill, Burton, Minier et al. in prep.) 403 clumps toward 131 fields 250 mm-only clumps (no radio, no maser, no MSX) n H 2  r -2

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

SPIRE & PACS 30’’ Need for Herschel SPIRE/PACS  m SED maps; Image clumps i.e. protoclusters; SPIRE key project on Star Formation

30’’ Need for ALMA Need subarcsec angular resolution: ; Resolve clumps/protoclusters into cores and massive protostar multiple systems M  pc -3 2’’= kpc 5’’ Minier et al.’04, Longmore et al. in prep Submm Cm cont. on MIRCm cont. on NIR 10 4 M  pc -3

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

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

Mopra - 13 CO integrated map Cold clump

Mopra - HCO + map Cold clump

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

Example 2: MIR dark cloud SED

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

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