Outflow, infall, and rotation in high-mass star forming regions Riccardo Cesaroni Osservatorio Astrofisico di Arcetri High-mass vs low-mass: the dividing line The formation of high-mass stars: accretion vs coalescence Observations: infall, outflows, and disks Kinematical evidence supports accretion ≡≫≪ 10M⊙  ′″∼

Low-mass vs High-mass Theory (Shu et al. 1987): star formation from inside-out collapse onto protostar Two relevant timescales: accretion  tacc = M*/(dM/dt) contraction  tKH = GM*/R*L* Lowmass (< 8 MO): tacc < tKH Highmass (> 8 MO): tacc > tKH  accretion on ZAMS

PROBLEM: High-mass stars “switch on” still accreting   radiation pressure stops accretion   stars > 8 MO cannot form!? SOLUTIONS Yorke (2003): Kdust< Kcrit  M*/L* “Reduce’’ L*: non-spherical accretion “Increase’’ M*: large accretion rates Reduce Kdust: large grains (coalescence of lower mass stars)

Possible models (Non-spherical) accretion: Behrend & Maeder (2001); Yorke & Sonnhalter (2002); Tan & McKee (2003) ram pressure > radiation pressure Coalescence: Bonnell et al. (2004) many low-mass stars merge into one massive star

Implications & predictions Accretion infall  disks  outflows isolated star formation possible massive stars form at cluster centre: (dM/dt)  FWHM3 (Shu et al. 1987) massive stars form with lower mass stars: t  M*1/4 (Tan & Mc Kee 2003)

Implications & predictions Coalescence infall, low-mass disks, multiple outflows isolated star formation impossible massive stars form at cluster centre: large n* (108 */pc3 !)  many collisions massive stars form after lower mass stars

best discriminant between models: kinematics of molecular gas infall: accretion  large accretion rate coalescence  small(?) accretion rate outflow: accretion  single massive flow coalescence  multiple low-mass flows rotation: infall+ang. mom. conservation   rotating disks (“only’’ in accretion model)

best discriminant between models: kinematics of molecular gas infall: accretion  large accretion rate coalescence  small(?) accretion rate outflow: accretion  single massive flow coalescence  multiple low-mass flows rotation: infall+ang. mom. conservation   rotating disks (“only’’ in accretion model)

best discriminant between models: kinematics of molecular gas infall: accretion  large accretion rate coalescence  small(?) accretion rate outflow: accretion  single massive flow coalescence  multiple low-mass flows rotation: infall+ang. mom. conservation   rotating disks (“only’’ in accretion model)

best discriminant between models: kinematics of molecular gas infall: accretion  large accretion rate coalescence  small(?) accretion rate outflow: accretion  single massive flow coalescence  multiple low-mass flows rotation: infall+ang. mom. conservation   rotating disks (“only’’ in accretion model)

Discriminating between models: observations Observational problems: IMF  high-mass stars are rare formation in clusters  confusion rapid evolution: tacc=20 MO /10-3MOyr-1=2 104yr large distance: >300 pc, typically a few kpc parental environment profoundly altered Advantage: very luminous (cont. & line) and rich (molecules)!

High-mass star forming region 0.5 pc

G9.62+0.19 NIR J+H+K 10 pc

G9.62+0.19 350 micron 0.5 pc Hunter et al. (2000)

Testi et al. Cesaroni et al.

Infall Difficult to reveal: Vff  R-0.5 direct evidence: red-shifted (self)absorption: ambiguous… position-velocity plots/channel maps indirect evidence: lack of support: Mgas > Mvir model fit to SED dM/dt=10-3—10-2 MOyr-1  accretion possible insufficient resolution: infall on single star?

Infall Difficult to reveal: Vff  R-0.5 direct evidence: red-shifted (self)absorption: ambiguous… position-velocity plots/channel maps indirect evidence: lack of support: Mgas > Mvir model fit to SED dM/dt=10-3—10-2 MOyr-1  accretion possible insufficient resolution: infall on single star?

Infall Difficult to reveal: Vff  R-0.5 direct evidence: red-shifted (self)absorption: ambiguous… position-velocity plots/channel maps indirect evidence: lack of support: Mgas > Mvir model fit to SED dM/dt=10-3—10-2 MOyr-1  accretion possible insufficient resolution: infall on single star?

Outflow Easy to detect even with low angular resolution single-dish (>10” i.e. >0.5 pc) CO surveys of UCHIIs, IRAS sources, masers (Shepherd & Churchwell 1996; Zhang et al. 2001; Beuther et al. 2002, etc.), H2 (shocked) 2.2m emission outflows in high-mass stars do exist typical parameters: 1 pc, 5—5000 MO , 10-4—10-2 MO yr-1, dM/dt  L0.7 BUT… are these from the most massive (proto)star?

CO(2-1) outflow & 1mm continuum Beuther et al. (2002)

Outflow Easy to detect even with low angular resolution single-dish (>10” i.e. >0.5 pc) CO surveys of UCHIIs, IRAS sources, masers (Shepherd & Churchwell 1996; Zhang et al. 2001; Beuther et al. 2002, etc.), H2 (shocked) 2.2m emission outflows in high-mass stars do exist typical parms.: 1 pc, 5-5000 MO , 10-4-10-2 MO yr-1 dM/dt  L0.7  continuity from low- to high-mass BUT… is outflow from one massive (proto)star?

CO outflows in YSOs Churchwell (2002) dM/dt  L0.7

Outflow Easy to detect even with low angular resolution single-dish (>10” i.e. >0.5 pc) CO surveys of UCHIIs, IRAS sources, masers (Shepherd & Churchwell 1996; Zhang et al. 2001; Beuther et al. 2002, etc.), H2 (shocked) 2.2m emission outflows in high-mass stars do exist typical parms.: 1 pc, 5-5000 MO , 10-4-10-2 MO yr-1 dM/dt  L0.7  continuity from low- to high-mass BUT… is outflow from one massive (proto)star?

 infall/outflow insufficient to prove model interferometric (>1” i.e. 0.05 pc) observations of selected targets in CO, HCO+, SiO, etc. (PdBI, OVRO, BIMA, NMA) “single-dish’’ outflows resolved into (massive & collimated) multiple outflows (Beuther et al. 2002) precession of outflow complicate interpretation (Shepherd et al. 2000; Gibb et al. 2003) powering source difficult to identify  infall/outflow insufficient to prove model

CO(2-1) & mm cont. Beuther et al. (2002) single-dish (12’’ beam)

05358+3543 Beuther et al. (2003) interferometer (4’’ beam)

 infall/outflow insufficient to prove model interferometric (>1” i.e. 0.05 pc) observations of selected targets in CO, HCO+, SiO, etc. (PdBI, OVRO, BIMA, NMA) “single-dish’’ outflows resolved into (massive & collimated) multiple outflows (Beuther et al. 2002) precession of outflow complicate interpretation (Shepherd et al. 2000; Gibb et al. 2003) powering source difficult to identify  infall/outflow insufficient to prove model

IRAS 20126+4104 Shepherd et al. (2000) blue lobe red lobe H2 knots

IRAS 20126+4104 jet in H2 line

Cesaroni et al. (in prep.) IRAS 20126+4104 Cesaroni et al. (in prep.)

 infall/outflow insufficient to prove scenario interferometric (>1” i.e. 0.05 pc) observations of selected targets in CO, HCO+, SiO, etc. (PdBI, OVRO, BIMA, NMA) “single-dish’’ outflows resolved into (massive & collimated) multiple outflows (Beuther et al. 2002) precession of outflow complicate interpretation (Shepherd et al. 2000; Gibb et al. 2003) powering source difficult to identify  infall/outflow insufficient to prove scenario

Disks Circumstellar accretion disks predicted only by accretion model! Any evidence? Large scale (1 pc) rotating clumps seen in medium density tracers e.g. NH3 in G35.2-0.74 (Little et al. 1985) Small scale (<0.1 pc) many claims of rotating “disks’’…

Disks Circumstellar accretion disks predicted only by accretion model! Any evidence? Large scale (1 pc) rotating clumps seen in medium density tracers e.g. NH3 in G35.2-0.74 (Little et al. 1985) Small scale (<0.1 pc) many claims of rotating “disks’’…

CH3OH masers ATCA, EVN Ellingsen et al., Walsh et al. Minier et al. OH masers Merlin outflow sources Cohen et al. (2003) SiO & H2O masers VLA, VLBA e.g. Orion source I Greenhill NIR, mm & cm continuum BIMA, VLA jets/outflows in massive stars Hoare et al., Gibb et al. NH3, C18O, CS, C34S, CH3CN PdBI, OVRO, BIMA, NMA UC HIIs, Hot Cores Keto et al., Cesaroni et al., Zhang et al., …

CH3OH masers: stellar mass too low; H2 jets parallel to CH3OH spots (De Buizer 2003) SiO & H2O masers: outflow or disk ? NIR-cm cont.: confusion between disk and wind emission Molecular lines: kinematical signature of disk & outflow

CH3OH masers W48 Minier et al. (2000) M*=6 MO

H2O masers Cep A HW2 Torrelles et al. (1996)

SiO & H2O masers: outflow or disk? CH3OH masers: stellar mass too low; H2 jets parallel to CH3OH spots (De Buizer 2003) SiO & H2O masers: outflow or disk? NIR-cm cont.: confusion between disk and wind emission? Molecular lines: kinematical signature of disk & outflow core disk outflow outflow

G192.16-3.82 Shepherd & Kurtz (1999) 2.6mm cont. disk CO outflow

G192.16-3.82 Shepherd & Kurtz (1999) 3.6cm cont. & H2O masers

NGC7538S Sandell et al. (2003)

Cesaroni et al.; Moscadelli et al. IRAS 20126+4104 Cesaroni et al.; Moscadelli et al. M*=7 MO H2O masers prop. motions

Disks & Tori L (LO) Mdisk (MO) Ddisk (AU) M* IRAS20126 104 4 1600 7 G192.16 3 103 15 1000 6-10 NGC7538S 100-400 30000 40? G24.78 (3) 7 105 80-250 4000-8000 20… G29.96 9 104 300 14000 - G31.41 3 105 490 16000 B stars O stars

Gibb et al. (2002) Olmi et al. (2003) Beltran et al. (2004)

Beltran et al. (2004)

Beltran et al. (2004)

Gibb et al. (2002) Olmi et al. (2003)

Beltran et al. (2004) 1200 AU Hofner priv comm.

Disks & Tori L (LO) Mdisk (MO) Ddisk (AU) M* IRAS20126 104 4 1600 7 G192.16 3 103 15 1000 6-10 NGC7538S 100-400 30000 40 G24.78 (3) 7 105 80-250 4000-8000 20… G29.96 9 104 300 14000 - G31.41 3 105 490 16000 B stars O stars

Results “Circumcluster’’ (massive) tori in O (proto)stars Circumstellar (Keplerian) disks in early-B (proto)stars  Are disks in O (proto)stars short lived?

Assuming (dM/dt)acc  (dM/dt)outflow and Mdisk  M* disk ioniz. & accr. rates disk life time B stars O stars B stars O stars

Conclusions Circumstellar (Keplerian) disks in early-B (proto)stars  disk accretion likely Circumcluster (unstable) tori in O (proto)stars  large accretion rates make them long-lived ACCRETION SCENARIO MORE LIKELY

G45.47+0.05 NH3(2,2) red-shifted absorption Hofner et al. (1999) systemic velocity blue-shifted emission

Fontani et al. (2001) n  R-2.6

CO outflows in YSOs Beuther et al. (2002)