Outflow-Envelope Interactions at the Early Stages of Star Formation Héctor G. Arce (AMNH) & Anneila I. Sargent (Caltech) Submillimeter Astronomy: in the era of the SMA June 2005 Cambridge, MA

Introduction Most, if not all, protostars produce outflows Circumstellar envelopes (~ AU) are primary mass reservoirs of forming stars Outflows interact with circumstellar envelope: -Injection of momentum and energy -Shocks-induced chemistry Outflows may be responsible for envelope’s dispersal, ending infall stage and playing important part in the mass-assembly process Circumstellar envelope angular size scales ~10-30”, with complex velocity structure. High angular and velocity resolution observations are needed.

Observations Owens Valley Radio Observatory Millimeter Array Observed gas surrounding a sample of YSO with outflows at different evolutionary stages to study the morphology and kinematics of the molecular outflow and circumstellar envelope Using different molecular lines that trace different density (and kinematic) regimes: Simultaneously observe: 12 CO(1-0): low-density, high-velocity outflow 13 CO(1-0): “large-scale” (~0.05 pc) envelope C 18 O(1-0): inner (~0.02 pc) regions of envelope 2.7 mm continuum Simultaneously observe: HCO + (1-0): optically thick (infall)/shock chem. tracer HNC(1-0): high-density tracer H 13 CO + (1-0): high-density, optically thin tracer 3.4 mm continuum

12 CO(1-0) Outflow Survey 10 4 AU 20” HH114mmsRNO43 HH300 L1228RNO129 RNO91TTAU GKTAU IRAS3282 Class 0 Class I Class II

Opening Angle vs. Time TTau RNO129 RNO43 HH114mms IRAS3282 HH300 L1228 HH211 Gueth & Guilloteau 1999 RNO91 Lee & Ho 2005 Langer et al B5-IRS1 Lee et al IRAM04191 Ohashi et al L1551 Time

C 18 O(1-0) Emission: probing the circumstellar envelope 5000 AU 10” HH114mmsRNO43 HH300L1228RNO129 RNO91TTAU GKTAU IRAS3282 Class 0 Class I Class II

C 18 O envelope kinematics HH114mmsRNO43 HH300L1228RNO129 IRAS3282 rotationrotation/infall ?infall outflow ???? Class 0 Class I Class II No structured kinematics, but C 18 O emission (when detected) mostly blueshifted and close to blue outflow lobe.

C 18 O envelope mass vs. time Time Consistent with single-dish studies: Ladd et al Fuller & Ladd 2002

Evidence for Outflow-Envelope Interactions Outflow lobe widening with time: collimatedwide-angle clumpy mess/ very wide Class 0 Class IClass II Time Change in envelope morphology and kinematics with time: Decrease in envelope mass with time:

HCO + (1-0) outflow emission: outflow chemical impact Class 0 Class I Class II HH114mmsRNO43 HH300L1228RNO129 TTAU IRAS3282 Other HCO + outflow studies: Hogerheijde et al. 1998; 1999 Girart et al Consistent with chemical models: Rawlings et al. 2000; 2004 Viti et al. 2002

Studying outflow-envelope interactions with the SMA High transition lines will probe hot molecular gas closely related to shocks (at  ~ 1”). Potential for simultaneous multi-line observations e.g., 12CO + 13CO + C18O (2-1) 13CO + C18O (3-2) HCO+(3-2) + HCN(3-2) + 13CS(6-5) Outflow impact on envelope’s dust using sub-mm dust continuum emission HH114mmsPV Cep L1157 CO(2-1)1.3mm 800  m (Gueth et al. 2003)

Summary From observations of YSO sample: widening of outflow cavities with time change in envelope morphology and kinematics with time decrease in envelope mass with time These are consistent with a picture where outflows play a major role in evolution of circumstellar envelope HCO + observations show outflow-envelope interactions also affect the chemical composition of circumstellar environment, independent of outflow age. SMA observations will allow us to study the physical and chemical properties of gas closely related to shock, and impact of outflow on dust