An Evolutionary Model of Massive Star Formation and Radiation Transfer

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1 An Evolutionary Model of Massive Star Formation and Radiation Transfer Yichen Zhang Universidad de Chile Collaborators: Jonathan Tan (UF), Christopher McKee (UC Berkeley), Takashi Hosokawa (U. Tokyo), James De Buizer (NASA/SOFIA), Mengyao Liu (UF), Kei Tanaka (UF), Maria Drozdovskaya (Leiden) From Stars to Massive Stars, Gainesville, FL, Apr. 6-9

2 Evolutionary model Initial & Environmental Self-consistent evolutionary tracks for protostars, protostellar cores, disks, and outflow cavities Explore the effects of the initial & environmental conditions and evolution on various processes Protostellar properties Velocity Field Photoionization Simulation Ionization Structures /Thermal Histories along Streamlines Other Applications Radio, H recombination lines (spectra/images) (Tanaka, Tan, Zhang 2016; See Kei Tanaka s talk) Chemical Modeling Chemical Evolution (See Maria Drozdovskaya s talk and poster; see also Zhang & Tan 2015)

3 Initial : massive starless core in virial equilibrium, in pressure equilibrium with surrounding medium, singular polytropic sphere, will collapse from inside out (Turbulent Core Model, McKee & Tan 2003) Initial Condition Parameters: Initial core mass Mc Surface density of the clump Ʃcl Surface pressure on the core Core radius Rotation-to-gravitational energy ratio βc (~0.02) Disk sizes Outflow P~GƩ 2 Core Star or close binary Clump cluster Core Disk (Zhang et al. in prep.; Zhang, Tan, Hosokawa 2014; Zhang, Tan, McKee 2013; Zhang & Tan, 2011) Ambient Clump Pressure P~GƩ 2

4 Evolution with protostellar mass Outflow Opening Angle Accretion Rate Red: Mc =60 M, Ʃcl=1 g/cm 2 Blue: Mc =60 M, Ʃcl=0.3 g/cm 2 Stellar Radius Luminosity Protostellar Protostellar evolution + Disk evolution + Disk wind feedback + Core collapse (Zhang et al. in prep.; Zhang, Tan, Hosokawa 2014; Zhang, Tan, McKee 2013; Zhang & Tan, 2011)

5 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=1m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

6 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=2m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

7 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=4m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

8 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=8m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

9 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=12m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

10 Mc =60 M, Ʃcl=1 g/cm 2, βc=0.02 Mc =60 M, Ʃcl=0.3 g/cm 2, βc=0.02 (Code: Whitney+ 03, 12; also see Robitaille+ 11) SED m*=16m Images 8 μm 20 μm 37 μm 8 μm 20 μm 37 μm

11 Model grid 4+3 parameters: Ʃcl, Mc, βc, mstar, d, inc., AV Determine the evolutionary tracks (Zhang, Tan+. in prep.) Determine the current stage Ʃcl : 0.1 ~ 3 g/cm 2 (4) Mc : 10 ~ 500 (9) βc : 0.02 mstar: 0.5 ~ 100 (12) : (4500) + (d, AV) Determine how it is viewed Observation (De Buizer et al. in prep.; also see Zhang, Tan, De Buizer+ 2013) SOfia MAssive star formation (SOMA) survey (PI: Tan): Imaging by SOFIA-FORCAST in 10 ~ 40 μm. High to intermediate-masses; Different evolutionary stages; Different environments (isolated, crowded) 8 sources reduced, 14 sources observed, ~50 sources planed. (see Mengyao Liu s poster 71)

12 SED model grid: 5 free parameters currently, 4500 (Zhang, Tan+. in prep.) Observation: SOFIA 7.7 ~ 37 μm continuum imaging (See Mengyao Liu s poster 71; De Buizer et al. in prep.;) SOFIA 37μm Current model grid fitting Robitaille+ 06, 07 (Ʃcl, Mc, mstar, inc., AV) (14+3 parameters, 200,000 ) Mstar(M ) Ltot(L ) 4.8E E+04 IRS 9 30 scale bars 30 scale bars ṁdisk(m /yr) 1.8E E-06 Mstar(M ) ṁdisk(m /yr) 7.6E-04 Ltot(L ) 5.2E E+04 Mstar(M ) ṁdisk(m /yr) 2.8E E-09 Ltot(L ) 7.0E E+04 Mstar(M ) 8 11 ṁdisk(m /yr) 4.1E E-07 Ltot(L ) 9.7E E+03

13 Summary We have constructed a self-consistent evolutionary model for massive star formation, based on the Turbulent Core Model. We construct evolutionary tracks from initial and environmental conditions, and include the collapse of the envelopes, growth of the accretion disks, opening-up of the outflow cavities, and evolution of the protostars. Such a model can be coupled with different types of radiative transfer and chemical simulations to predict observations. With continuum radiative transfer, we constructed an SED grid which can fit the observations with small number of parameters, which indicates that the behavior of the multiwavelength IR continuum emission of massive protostars can be explained by evolution sequences and the variety of initial & environmental conditions.