Molecular Outflows from Low- to High-Mass Star Forming Regions Debra Shepherd, NRAO Hctor Arce, AMNH Rafael Bachiller, OAN Henrik Beuther, Max Planck Frdric Gueth, IRAM Chin-Fei Lee, SMA Alex Rosen, Armagh Obs Contents Introduction Outflow properties from observations Outflows from low- & high-mass protostars Summary of similarities & differences Entrainment & Jet Propagation models Entrainment mechanisms models Comparing observations and models Impact of outflows on the surrounding environment Physical impact: gas dispersal & turbulence Shock chemistry Future research & conclusions Introduction Outflows provide critical angular momentum transport from the disk, allowing accretion to proceed beyond ~0.1 Msun Outflow & infall dynamics affect: Energy input & turbulence in molecular clouds Chemical composition of the host cloud Dissipation of molecular gas, especially close to forming star Final mass of the central star Disk (and planet) evolution Outflows provide a fossil record of mass-loss history of a protostar (or protostellar cluster). Massive versus low-mass protostellar outflows: OB stars usually form in clusters expect more dynamical interactions Expect massive YSO to evolve to ZAMS more rapidly: O stars: t evolve ~ few x 10 4 yrs, G star: t evolve ~ few x 10 7 yrs OB stars reach ZAMS while still embedded increased radiation pressure may affect outflow dynamics Outflows from low-mass prototars HH 211 Higher transition SiO more highly collimated (Hirano 2005, Chandler & Richer 2001) Very young molecular flows are highly- collimated. Example: HH 211(age ~ 10 3 years). Compare CO (white contours), H 2 (color), & 1 mm continuum (red contours) (McCaughrean et al. 1994, Gueth & Guilloteau 1999). Low- velocity gas surrounds higher velocity gas. Low velocity High velocity Outflows from low-mass protostars NGC 1333 IRAS 2 (Loinard et al., in prep) High-velocity SiO more collimated than low- velocity. SiO emission traces the molecular jet not the strong terminal shocks against the ISM. Red & blue contours: higher velocity SiO Black contours & grey scale: lower velocity SiO Outflows from Low-mass protostars Evolution: opening angle widens with time jet wide-angle flow + jet (both components appear to exist) L1228 (IRAS ): CO(1-0) red and blue- shifted emission, 2.7 mm continuum. Grey: H2 emission. (Arce & Sargent 2005) Morphology & kinematics consistent with entrainment by an underlying wind that has both wide-angle wind and collimated jet components. Wide angle cavity excavated by the wind. molecular outflow axis Opening angle vs source age (derived from T bol ). Opening angle increases significantly with time. (Arce & Sargent, in prep) 16 o 160 o Outflows from Low-mass protostars Outflows Precess - increases interaction with environment. Interact with core. mm continuum: core (300 AU) & envelope (3000 AU). Warm dust from core extends into outflow. Core tracer, HC 3 N show structures extending into outflow lobes. L1157 CO shells trace jet bow- shocks. SiO traces shocks near head of precessing jet (Gueth et al. 1998) SiO CO Interaction between molecular outflow & nearby protostellar environment (Beltran et al. 2004) CO+2.7mm CO+1.3mm CO+HC 3 N CO+C 18 O 20 Early B Protostar ~ 10 4 years old IRAS B protostar cluster Beuther et al. (2002, 2004) Sridharan et al. (2002) 3 or 4 early B protostars (not on Main Sequence yet) CO outflows are well collimated No cm continuum emission detected perhaps accretion is so large that UC HII region is quenched? Thus, effects of stellar UV radiation field absent or minimized. Molecular flows produced by early B protostars can be highly collimated. Early B Protostar ~ 10 4 years old Lebron et al. (in prep) Cesaroni et al. (1999,2004,2005) Hofner et al (1999,2001, in prep) Moscadelli et al. (2000, 2005) Shepherd et al. (2000) Zhang et al. (1998, 1999) B0.5 Protostar (not ZAMS but cm continuum detected) Extreme precessing jet creates wider angle CO outflow 2000 AU rotating torus & 10,000 AU rotating NH 3 core IRAS Estimated jet full opening angle ~ 34 o (from model of VLBI H 2 O maser emission). Consistent with derived from SiO jet. Compare: LM jets have ~ o within 10 AU of star that re-collimate to 1-3 o within 100 AU. No re-collimation obvious. H & CO(1-0) Early B Stars ~ 10 5 years old G Indebetouw et al. (2003) Devine et al. (1999) Shepherd et al. (1998,1999,2001) [SII] CO(1-0) 7 mm continuum & model K-band YSO Collimation consistent with wind-blown bubble Evidence for 100AU accretion disk, 1000AU rotating torus NH 3 core not graviatationally bound near end of accretion phase B2 ZAMS star & UC HII region 40 o -50 o opening angle outflow O Protostars explosive events Subaru J, H, K Images Orion H 2 fingers Explosive event forming fragmented stellar wind bubble (McCaughrean & Mac Low 1997, Cunningham et al. 2005) Dynamical time scale ~ 1,000 years. May be caused by interaction between BN and Source I. G34.26 Star Cluster Churchwell et al. (2004) Spitzer/GLIMPSE image: 3.6 m (blue), 4.6 m (green), 5.8 m (orange), 8.0 m (red). Interaction or Coalescence? Source I & BN proper motions: within 0.5 (225 AU) of each other 500 years ago stellar system disintegrated in recent past Rodriguez et al. (2005)? Or BN ejected from 1 Ori C and past Source I (Tan 2004)? If final M independent of clump mass young O star can look like mid-B star. Comparison: evolutionary scenario Proposed OB star evolution (Beuther & Shepherd 2005): Three morphologies produced by 2 possible sequences: TOP: evolution of early B star from HM protostellar object via HCHII region to UC HII region BOTTOM: evolution of an O star which transitions from B & late O-type stages to final M & L T Tauri star evolution (Fuller & Ladd 2002, Arce & Sargent, in prep): Class 0 Class I/II 10 3 yrs yrs Begin very collimated in Class 0 phase. Wide angle wind strengthens during Class I phase. Fast, collimated jet becomes weaker but never disappears until accretion halts Early B protostar HC HII UC HII Early O B1-O8 B5-B yrs ~10 4 yrs 10 5 yrs 10 2 yrs yrs 10 4 yrs ZAMS Outflow Entrainment M f a function of entrainment efficiency?. P f E f L bol 0.6 for L bol = 0.3 to 10 5 L sun Strong link between accretion & outflow.. Cabrit & Bertout 1992, Shepherd & Churchwell 1996, Anglada et al. 1996, Henning et al CO Outflows from low and high- mass stars show a mass-velocity (MV) relation dM(v)/dv ~ v = 1 to as high as 10; becomes steeper with age & flow energy Rodriguez et al. 1982; Lada & Fich 1996; Shepherd et al. 1998; Richer et al. 2000; Beuther et al dM(v)/dv to v break (CO) v to to to Early B star outflows T Tauri star outflows PfPf. L bol MfMf. L acc L ZAMS F = L bol /c (Wu et al. 2004) (Beuther et al. 2002) L bol Entrainment/Outflow Propagation Models Arce & Goodman (2002) A few contributions: Turbulent jet: Cant & Raga 1991; Stahler 1994; Lizano & Giovanardi 1995; Micono et al. 1998, Molecular jet bow shock: Hydro: Raga & Cabrit 1993; Downes & Cabrit 2003; Rosen & Smith 2004, 2005; Raga, Williams & Lim 2005; Keegan & Downs 2005 MHD: Stone & Hardee 2000; Frank, Gardiner et al ; Cerqueira & de Gouveia dal Pino 2001; OSullivan & Ray Wide-angle wind: Shu et al. 1991; Li & Shu 1996; Lee et al. 2001; Raga et al. 2004; Cunningham et al Circulation model: May be necessary for massive flows to account for large masses: Fiege & Henriksen 1996: Lery et al. 1999, 2002, 2004; Aburihan et al 2001. Jet Propagation Models Downes & Cabrit (2003) 2D, hydrodynamic, bow-shock model. Low density, fast jet, no post-shock mixing Intensity-velocity relation similar to observations in many cases, slope steepens with age. Kinematics not quite right: gas expands perpendicular to jet axis difficulty obtaining adequate forward-motion. CO(2-1) pulsed jet at t = 400 yrs X (1x10 14 cm) (g cm -3 ) Internal working surfaces Jet Models Rosen & Smith (2004), Smith & Rosen (2005) Zeus-3D, hydrodynamic model with molecular cooling and limited C & O chemistry. CO outflow lobe created by jet with 20 o / 50 year (fast) precession 60 year pulsation Note: Slower, pulsed flows have adequate forward motion can reach parsec distances in 3-10 x 10 4 years Jet: 100 km/s, 100 K, 2x10 19 g cm -3 Ambient cloud: 10 K, 2x10 20 g cm -3 y x Jet Models Rosen & Smith (2004) H 2 (1-0) in jet flow with 20 o fast precession HD jet models can reproduce morphology of some observed flows but kinematics still a challenge: dM(v)/dv ~ v = 1.4 to 3 but doesnt match in observed wider angle and more powerful flows wide angle wind still needed? Observations: Flows with larger tend to be poorly collimated often need wide-angle wind to reproduce flow kinematics. Models: Wide-angle wind models yield shallower slopes not consistent with observations. Wind propagation models Cunningham et al. (2005) wide-angle wind model. Cylindrical symmetry (2.5D), hydrodynamic adaptive mesh refinement. Applied to Orion I to examine inner regions of a wide-angle wind which could produce larger flow. T=7 years Outflow unstable, fragments into clumps as seen in Orion. Observed morphology of cavity shell, gas rotation, proper motion and line-of-sight velocity approximately reproduced by the model. Wind-driven outflow good model for this explosive outflow. Application to lower-mass flows? MHD Jet Propagation models Frank, Gardiner et al. ( ) Ideal MHD jet bow-shock models. Jet configuration derived from analytical models for magneto-centrifugal launching. Gardiner & Frank (2000) Pulsed Jet: B-field geometry changes with time. Density and toroidal field strength correlated. Poloidal field strength high between knots. T=365 years n [cm -3 ] B [ G] Poloidal field lines Toroidal field strength 1000 AU Frank et al. (2000) Magneto-centrifugally launched jet from Keplerian disk-wind: separation of inner jet core from low density collar (jet within a jet). Compare with observations: Compression of B toroidal may be violent & unstable on small scales. Possible B- field reversals & reconnection should have observational and dynamical consequences. L1448, SiO(2-1) L1157, SiO(2-1) HH211, CO(2-1) Physical impact: gas dispersal & turbulence Outflows have been proposed to be a major source of turbulence in a star forming core. Consider: G , an early B star still accreting (Shepherd et al. 2004). NH 3 core is clumpy and not gravitationally bound is it being dispersed by the embedded protostars? Small Scales: Large Scales: Giant outflows from young stars of all masses are common and they can interact with cloud gas > 1 pc from their YSO. In some cases E flow ~ binding and turbulent energy of cloud. L1551 PV Cep 0.5 pc 1 pc Greyscale: 13 CO cloud Blue and Red Contours: 12 CO outflow Devine, Reipurth & Bally (1997) Reipurth, Bally & Devine (1997) Moriarty-Schieven & Snell 1988; Pound & Bally 1991 Arce & Goodman 2002 G early B ZAMS G192 S3 Physical impact: gas dispersal & turbulence Outflows interact with their core & envelope There is an evolution in the outflow-envelope interaction. Outflows can limit star formation efficiency Class 0 Class I Class II time Red & blue contours: CO outflow Green contours: Core emission (NH 3, HCO +, N 2 H + ) Color: H 2 & IR reflection nebulae HH212 L1228 RNO91 Lee et al Wiseman et al Lee & Ho 2005 Arce & Sargent 2004 Physical impact: Shock chemistry Consider L 1157 (Bachiller et al 2001): Class 0 source with high inclination easier to study shock chemistry (less confusion) Chemical anomalies in molecular flows evolve with time indication of age. N 2 H + : pre-protostellar condensations, disks. Destroyed by dissociative recombination & reactions with H 2 O, CO. HCO +, enhancement ~20, only seen close to YSO SiO, enhancement ~10 6, highest velocity wings, low velocity SiO not well understood, shock pre-cursor? Sulfur chemistry potential tool to construct chemical clocks to date outflows, perhaps use SO 2 /CS and CS/SO ratios to constrain age (Wakelam et al 2005) CH 3 OH, H 2 CO, enhancement ~100, more volatile than SiO, does not survive at high velocities. Possibly marks later stage in shock evolution than SiO. Physical impact: Shock chemistry Interpretation of data from most shocked regions in outflows suggest a combination of C- and J-shocks associated with episodic outflow ejection. Shock type affects entrainment mechanism. H2 & [FeII] found in flows from low-mass YSOs. Morphology similar on large scales but details differ. Physically different mechanisms produce emission. Consider HH 211 (Connell et al. 2005) CO(2-1) H S(1) m H S(1) m [FeII] m C-type bow [FeII] H2H2 J-type bow H2H2 One massive outflow from an early B star studied in similar detail: W75N (Shepherd, Testi & Stark 2003). H2 is strong but [FeII] absent in flow excitation conditions may differ from flows generated by low-mass stars Future Research We have general properties & evolutionary trends, but results rely on a limited number of outflow maps statistical analysis dangerous. Need larger sample of well-studied flows. Use existing telescopes: ALMA (2012) at 1 resolution. Study entrainment & chemical processes in flow & cloud-outflow interaction. SMA: Submillimeter imaging, esp. CO(6-5) 1 st time at sub-arcsec resolution! Trace flow closer to driving source & jet. Study shock chemistry with multi-line, simultaneous observations. IRAM PdBI: Upgrade over next several years. Increase sample of mosaic maps of clouds & outflows at 1 & 3mm. EVLA: (2012) Image wide- opening angle And new instruments: HSO: (2007) Measure shock tracers, esp H 2 O not available from ground. CARMA: Multi-line mosaic images ionized gas close to source, re- ionization events in jets, H 2 O masers, & SiO(1-0) in flows. Sub-arcsec resolution, single-dish+short spacing high-fidelity kinematics & morphologies of distant flows. Study flow ejection from disks, entrainment, and energy transfer to core. Greater computing power. Conclusions T Tauri to late O protostars have accretion disks & outflows that can be well-collimated. Jet+wind driven models needed to explain morphology & kinematics Evolutionary difference: - Low-mass flows show evidence for 2-component wind (jet+wide-angle) through out entire life. Flows widen with time. - Once early B star reaches ZAMS, associated ionized outflows have strong wide-angle winds. Jet component often not detected. Mid to early O stars: Outflows appear to be poorly collimated. Explosive events interactions. Coalescence a possibility in some cases. Outflows disrupt environment: from circumstellar envelopes (~10 3 AU) to molecular cloud (1-10 pc). J & C-shocks produce chemistry that may act as a chemical clock to date outflow ages The future is bright with new instruments being brought on-line or soon to be built.