Accretion-Disk-outflow System in High Mass Star Formation. Yuefang Wu Astronomy Department Peking University, China

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1 Accretion-Disk-outflow System in High Mass Star Formation Yuefang Wu Astronomy Department Peking University, China

2 Outline 1. A debate two models of high mass star formation 2. Our related work- observational evidence (1). Statistics of molecular outflows (2). Studies of collapse signatures with single dish Core JCMT18354 A survey (3). High angular resolution study of individual sources Inflow motion associated with bipolar outflow Core JCMT18354 Core W3-SE Possible inside out collapse in the core of G Summary and further work

3 1. A debate Less understood for massive star formation than for that of low mass ones Two opposing views: Problem: for forming stars with 8 M radiation pressure halts infalling (Wolfire & Cassinelli 1987) Collision- coalescence of less massive stellar objects: -- high-mass star usually form in dense clusters -- to avoid the radiation problem (Bonnell et al.1998, 2004) Stellar source density required: pc -3 Accretion-disk-outflow still Theory development could overcome the above problem help of disk, outflow (Jijina & Adams 1996; Yorke & Sonnhalter 2002; Klumholz et al. 2005; Keto 2007 ) To see the vitality of these two model inflow and outflow motion, disk structure key evidence Whitney 2005

4 2. Our related observational evidence (1). Statistics of molecular outflows I Lada 1983 II Fukui 1989 III Wu et al IV Wu et al. (2004) Total 397 High mass group 139 Low mass group 223 (29 can not be classified) % -high mass outflows --- Only one outflow was produced from collision Outflows driven by stellar source are common in high mass star formation regions Barsony 1989 S87 Xue & Wu 2008

5 (2). Studies of collapse signatures with single dish: Core JCMT S: Blue profile in high mass star formation (Wu, J. & Evans 2003), but single point -- signature peak -- associated outflow? Mapping study : First source: Core JCMT Massive core detected with NH3 lines (Wu, Zhang, Yu, Miller, Mao, Sun, Wang 2006) SCUBA contours on MSX E band ( um) Left: 450 um Right: 850 um 800 M

6 Optical Thick: HCN (3-2) HCO+(3-2) Optical thin: H13CO+(3-2) C17O (2-1) multiple evidence for blue profile Model fitting using the one of Myers et al. (1996) Signature: center gravitational collapse with outflow (Wu, Zhu, Wei, Xu, Zhang, Fiege 2005) Molecular outflow: CO (3-2) ΔV ~ 38 km/s, t ~ estimated 6600 yr.

7 A mapping survey Motivation: Further identify (exclude other motion) Parameters * Tendency of variation with time? Blue excess: E= (Nb-Nr) / Nt Nt: total sources of the survey Nb: number of detected sources with blue profile Nr: number of detected sources with red profile detected Wu, Henkel, Xue, Guan, Miller 2007 Samples: Different evolutional phases: I: Precursors of UC HII regions (PUCHs) including starless cores (according to IRAS and MSX) II: UC HII regions (II) Total 46 I: 33 II: 13 Results: E of HCO+ (1-0) UC HII 58% PUCHII 17% Contrary to the theoretical result ( Wolfire & Cassinelli 1987) Low mass sources: Class I 0 I E:

8 (3). High angular resolution study of individual sources Inflow motion associated with bipolar outflow (Liu, Wu, Zhang, Ren, Guan, Zhu in preparation) Core JCMT18354: observed with SMA at GHz in Sep mm continuum image Left. Compact Right: extended 130 M Inflow signature HCN (3-2) HCN (3-2) outflow

9 W3-SE: An NH3 core Observed with JCMT IRAM IRAM map Wu, Henkel, Xue, Guan, Miller 2007 IRAM map Wu, Henkel, Xue, Guan, Miller 2007 Tieftrunk et al. 1998

10 CARMA, observed in 2008, July 3.4 mm, HCO+ J=1-0, 70 M Zhu, Wright, Zhao, Wu 2009 SMA, observed In 2008, Oct. 1.1 mm, HCN (3-2) Zhu et al. in preparation

11 Possible inside out collapse in the core of G Complex massive star forming region: Ionized region (Genzel & Downes 1977) nine UC HII region (Furuya et al. 2005) H2O, OH, CH3OH masers CH3CH2CN, HCOOCH3 A 3 mm core (Remjan et al. 2004) D: 4 kpc

12 IRAM results Wu, Henckel, Xue, Guan, Miller 2007

13 SMA data: (Wu, Qin, Guan, Xue, Ren, Liu, Huang 2009) Archive, observed at 2005, July Seven antennas were used GHz (Low-upper sideband) beam 2.3 x2.0 (P.A.=14 o.4) Result: A continuum core: very compact 6000 au 15 M (Td: 552 k) CO J=3-2, 13CO J=3-2 CN N=3-2 CH3CN: 8 lines

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15 CO J=3-2 Vin: 3.5 km/s CN N=3-2 Vin: 6.0 km/s dm/dt=6.1x10-3 M /yr Pure free infall: dm/dt=4.3x10-3 M /yr Vin (CN) > Vin (CO) inside out collapse (Shu 1977)

16 3. Summary and further work Outflows and inflow signatures obtained show that high mass stars may form via accretion-disk-outflow process To continue investigations of morphology and variation with time of inflow motions To make model analysis

17 Thank you!