Multi-Physics of Feedback in Massive Star Formation

Transcription

1 Multi-Physics of Feedback in Massive Star Formation Rolf Kuiper1,2 H. W. Yorke3, N. J. Turner3, T. Hosokawa4 1 - Institute of Astronomy and Astrophysics, University of Tübingen, Germany 2 - Emmy Noether Program of the German Research Foundation 3 - Jet Propulsion Laboratory, California Institute of Technology, CA, USA 4 - Physics Department, University of Tokyo, Japan From Stars to Massive Stars Gainesville, Florida, USA April 7, 2016

2 Feedback in Massive Star Formation Ionization / HII Regions l l e t s o t Pro s w tflo u O ar Radiation Pressure on Dust Rolf Kuiper Multi-Physics of Feedback in Massive Star Formation April 7, 2016

3 Time Feedback mechanisms in chronological order: Protostellar Outflows Pre-main sequence Radiation Pressure Ionization / HII Regions Main sequence Stellar Winds / Mass Loss Supernova Simulation Approach: Focus on small spatial scales (Rsink = 3 AU; Δxmin = 0.3 AU) Focus on long-term evolution (tend = 6 tfree-fall) Multi-Physics Feedback Rolf Kuiper Multi-Physics of Feedback in Massive Star Formation April 7, 2016

4 Simulation Approach Kuiper et al. (2011), ApJ 732

5 Software Development / Multi-Physics (Magneto-)Hydrodynamics PLUTO 4 (Mignone et al. 2007, 2012) Self-Gravity (Kuiper et al. 2010b) Stellar Evolution Module (Kuiper & Yorke 2013) Dust Sublimation and Evaporation Module Protostellar Outflow Module (Kuiper, Yorke, & Turner 2015) Radiation Transport Irradiation + Diffusion Hybrid Scheme (Kuiper et al. 2010a) now also in FLASH 4 (Klassen et al. 2014) & ORION (Anna s talk) Hydrogen Ionization Direct Stellar EUV Flux Diffuse EUV Recombination Flux (in contrast to on-the-spot ) Kuiper & Mignone (in prep.) not to scale

6 Simulations Overview Protostellar Outflow series (Kuiper, Turner, & Yorke, in prep.) Collimation (3 different) Accretion/Outflow efficiency ~ 1, 10, 20, 30, 40, 50% 11 Simulations Multi-Physics series: 100 Msol in 0.1 pc and 1% Outflow Strength 100 Msol in 0.1 pc and 10% Outflow Strength 1000 Msol in 1 pc and 10% Outflow Strength 36 Simulations Dimension: 2D (axial and midplane symmetry) or 3D In total: > 50 simulations Finite Mass Reservoir Infinite Mass Reservoir

7 Simulations Overview Multi-Physics Feedback Stellar Radiation Pressure Thermal Radiation Pressure Stellar Ionization Recombination Ionization Sim 1 Sim 2 Sim 3 Sim 4 Sim 5 Sim 6 Sim 7 Sim 8 Sim 9 Sim 10 Sim 11 Sim Combinations

8 Results of Multi-Physics Simulations ~10 4 AU or 0.05 pc Protostellar Outflow collimates due to in-falling Envelope Optically thick Disk causes Shadow Stellar Radiation Pressure and Direct Stellar Ionization Feedback limited to bipolar Regions ~ 600 AU

9 Stellar vs. Thermal Radiation Pressure ( * [ - ]) Thermal Radiation Pressure Stellar Radiation Pressure Both * [ ] Thermal Radiation Pressure Feedback dominates on envelope-to-disk accretion Stellar Radiation Pressure Feedback eventually shuts off disk-to-star accretion

10 Radiation Pressure vs. Ionization ( * [ - ]) Radiation Pressure Ionization Both * [ ] Both forces act on bipolar regions Both effects require / dominated by EUV spectrum Radiation Pressure + Ionization rather Merging than Adding up

11 Chronology of Feedback Efficiency ( * [ - ]) Protostellar outflows + Thermal Radiation Pressure + Stellar Radiation Pressure + Ionization * [ ] Open Question: Does the Feedback shut off Accretion? or Does the Feedback only reduce the available Mass Reservoir for Accretion?

12 Finite vs. Infinite Mass Reservoirs Extending the Mass Reservoir from 100 Msol in 0.1 pc to 1000 Msol in 1 pc sphere, preserving the initial slopes of density and angular momentum. 0.1 pc 1 pc

13 Finite vs. Infinite Mass Reservoirs Chronology of Feedback Efficiency Mres = 1000 Msol ( * [ - ]) Protostellar outflows + Thermal Radiation Pressure + Stellar Radiation Pressure + Ionization Mres = 100 Msol * [ ] Protostellar Outflows rather unimportant (as a limiting Feedback effect). Stellar Radiation Pressure (and Ionization) dominate Feedback! Stellar Radiation Pressure is able to shut off Stellar Accretion!

14 Finite vs. Infinite Mass Reservoirs Chronology of Feedback Efficiency Mres = 1000 Msol ( * [ - ]) Protostellar outflows + Thermal Radiation Pressure + Stellar Radiation Pressure + Ionization Mres = 100 Msol * [ ] Speculations: Full Feedback Simulation will yield Mstar ~ 100+ Msol Formation of the most massive stars in the present-day universe (Mstar ~ 150 Msol) requires large mass reservoirs (~ 0.4 pc) are favored higher-density environments (Mres 100 Msol in 0.1 pc sphere) higher accretion rates (10-3 Msol/yr > Ṁstar > 10-2 Msol/yr). Talk by Rowan Smith! See also talk by Kei Tanaka!

15 3D (In-)stability of Massive Accretion Disks Spiral Arm Formation +330 yr ~50 AU Disks grow in time due to Angular Momentum accreted from large scales Formation of Spiral Arms (Disks are Toomre unstable) even at small radii Spiral Arms might fragment (Cooling vs. Dynamics) A direct pathway to close-in Massive Binaries!?

16 Position (A Massive Star Formation using FLASH 6.2. Two sources irradiating a dense core of material Specific Irradiation, r cases, approximate schemes such as flux-limited di usion must be used. We next create a test setup inspired by Rijkhorst et al. (2006), where a central concentration was irradiated by two sources. Since FLD methods are based on local gradients in the radiation energy, they cannot properly treat 101 shadowing. In this test we place a dense clump of material at the center of our simulation volume and irradiate (Fryxell et al. 2000, Dubey et al. 2009) it from two angles, creating a shadowed region. We com pute the irradiation and equilibrium temperatures. 103 Position (AU) Δ min Our setup contains a mix of optically thin and optically Fig. 12. Specific irradiation by two sources in an otherwise thick regions, creating strong gradients in the radiation homogeneous medium at = g/cm3, but for a central denenergy density. We compare the equilibrium temperasity concentration indicated by the black circle, where the density is = g/cm3. The two sources are stellar sources with eftures computed by the hybrid scheme to the temperature temperatures of 8000K. The flash block AMR structure is computed without Kuiper, di usion. Pudritz, Peters, Banerjee,fective (Klassen, Buntemeyer also shown, with each2014) block containing 83 cells. Klassen et al. The two radiation sources have a temperature Te = 8000 K and are situated in a low-density ( = due g/cm 3 ) medium to the side and below a central density concentration ( = 10 g/cm ) with radius Rc = nch cm 267 AU. The side length of the simulation ally box is about 2000 AU. Hydrodynamics are disabled. mic Figure 12 shows the simulation setup and the specific be irradiation of the gas in a slice through the midplane entof the simulation volume. The overlaid grid shows the 240 oreflash AMR block structure, with each block containing105 hese 3 8 cells and refining on gradients in density, radiation sion 200 energy, and matter temperature using the flash error described in section 3.1. The simulation was 1.0 estimator 160 run with a maximum 8 levels of refinement, achieving ial a maximum resolution of 1.96 AU. The black circle in t al. the centre marks the central density concentration. The density concentration casts a shadow on the side102 d by central gra- opposite of the central concentration. Figure 13 shows the gas temperature after the simureat 1 ate- lation has been given time to reach equilibrium. Here10 40 we see warming of a region just interior to the central iate where strong density gradients exist. om- overdensity of To visualize the radiation Position flux, (AU) we plot a vector field Position (AU) ally the radiation flux, given by equation 11. This is shown in Fig. 12. Specific irradiation by two sources in an otherwise Fig. 13. Same as in figure 12, but instead showing the gas 14 overplotted onat the total den-dention figure 20 radiation 3, but energy homogeneous medium = 10 g/cm for a central temperature. Rolf sity. KuiperThe vector field represents how the radiation Multi-Physics of Feedback in Massive Star Formation erasity concentration indicated by the black circle, where energy the density Temperature (K) Position (AU) Specific Irradiation, r F / (erg/s/g) Position (AU) Canadian - German Collaboration on Massive Star Formation Research FLASH 4 3D Cartesian AMR Grid, 11 levels of refinement, x = 10 AU Hybrid Radiation Transport Scheme April 7, 2016

17 Radiation Pressure dominated Cavities Klassen, Pudritz, Kuiper, Peters, Banerjee (2016) Kuiper et al. (2010, 2012) Kuiper et al. (2011) 1500 AU 1500 AU 1500 AU 1500 AU 1500 AU Krumholz et al. (2009) Expanding Cavities remain stable! See also Poster by Tim Harries!

18 Time Massive Accretion Disks Face-on view 3000 AU Edge-on view Results: Similar to Evolution of Disk at small radii Spiral Arm Formation (Toomre unstable) No Disk Fragmentation up to 40 kyr ~ 0.8 tff Next tasks: Cluster scale simulations Multi-Physics Ionization Turbulence Magnetic Fields

19 Emmy Noether Group on Massive Star Formation Magneto-Hydrodynamics of Jets & Outflows from Massive Protostars Anders Kölligan See Poster No. 63! Line-driven Ablation of Massive Accretion Disks Nathaniel Dylan Kee See Poster No. 61!