1. Douglas Lin Dept of Astronomy & Astrophysics, Univ California, Santa Cruz Kavli Institute for Astronomy & Astrophysics, Peking University in collaboration with Tingtao Zhou, Xu Huang, Matthias Gritschneder, Stephen Murray, Andi Burkert Cosmological Streaming: Inflows & Outflows Jerusalem, Dec 15 th, 2011 22 slides Multiphase medium in molecular clouds

2. 2/21 Region of star formation - M16 T. A. Rector & B. A. Wolpa, NOAO, AURA McCaughrean & Andersen 2002, A&A, 389, 513

3. Molecular cloud: Pipe Nebula Starless cores embedded in Pipe Nebula Pressure equilibrium with the surrounding warm medium Similarity between CMF & IMF CMF as the provenance of IMF 3/22 Lada et al 2008

4. Dense Core Mass Function Starless cores embedded in Pipe Nebula Pressure equilibrium with the surrounding warm medium Similarity between CMF & IMF CMF as the provenance of IMF global pressure confinement Similar mass function as IMF 4/22

5. Microphysics of thermal instability Norman & Krutsov Two phase medium balanced by pressure confinement Energy loss from hot medium through precipitation, not cooling Asymptotic thermal balance in the cold clouds due to external heating 5/22

6. Phase transition during collisions Density enhancement and recombination (Murray) 6/22

7. Growth of thermal instability Burkert Cooling vs sound crossing time From isobaric to isochoric cooling Power index of perturbation spectrum 7/22

8. Growth limits to thermal instability Conduction on small scales Heating of the hot medium 8/22

9. Sedimentation and heating Buoyancy effect of pressure confined clouds: sedimentation, drag, fragmentation Energy branching ratio Murray 9/22

10. Coagulation equation Starless CMF Dynamics of dense cores: Coagualtion Fragmentation … Thermal interaction Gravity collapse & SF Simulation results for evolution in 2Myrs (Huang et al 2011) First stars born 10/22

11. Bonner Ebert mass External pressure P ext Internal pressure T int gravity Critical Bonnor Ebert Mass Pressure confined Gravity confined Collapse ？ 11/22 M BE ~ T int 2 /P ext 1/2

12. Stellar Initial Mass Function Importance Kroupa IMF orion nebula 12/22

13. 13/21 Photoionization of warm medium Mach 1.5Mach 5Mach 7Mach 12.5 Gritschneder

14. Propagation of ionized region (  Oph) 14/22 whereIs the Stromgren radius Non spherical blister (Krumholz) Three phases: molecular cores, confining atomic gas, and tenuous ionized HII.

15. Triggered Induced star formation Sequential star formation First massive stars are born: uv radiation External temperature & pressure increased Bonnor Ebert Mass decreases Simultaneous core collapse Star burst 15/22

16. Induced Star Formation: Evaporation Effect Star heats up its vicinity  Dense cores evaporated?? =>R~0.05pc<Rc Evaporation negligible Ionization V.S Recombination 16/22

17. Nonthermal velocities in fragments Turbulence Bate et al 2010 Rotational fragmentation Ang mom conservation =>3 magnitude dispersion Andrews et al 201017/22

18. High angular momentum: Binary Systems New Bonnor Ebert Mass Previous Bonnor Ebert Mass Binary fragmentation: M=M1+M2 M1<M2 Define mass ratio: q= M1/M 0<q<0.5 18/22 Zhou et al 2012 Da Rio et al 2011 (Orion Nebula Cluster)

19. 19/21 Turbulence: angular momentum cancellation Surface density evolution & spin flip Disk may shrink to <0.1AU and be hot (1-2000K). CAIs may milt &re-condense after nebula resumes viscous diffusion & cools 19/22

20. 20/21 Supernova induced implosion DensityTemperature

21. 21/21 The Formation Time of CAIs From the spread among CAIs one can derive a relative condensation timescale of t≈20kyr From Pb-Pb measurements one can derive an absolute formation timescale of t≈4.6Gyr  The first generation of CAIs condensed 4.6 billion years ± 20 thousand years ago (e.g. Jacobsen et al, 2008, Earth and Planetary Science Letters 272, 353) Primitive CAIs Re-melted CAIs

22. Supernovae in dward galaxies (Fragile, Murray) Multiple massive stars Pregenitor HII regions Preferential ejection of Fe Preservation of H gas

23. Summary & discussion Multi-phase medium commonly co-coexist Interaction between cores and pressure confining gas determines CMF Cores mass function determines stellar IMF Clusters formation is triggered by radiative and supernova feedback Collective conduction between molecular cores, atomic, and ionized gas may regulate large scale cool stream flows 21/22

24. Thank you Happy Birthday Avishai 生日快乐 22/22 Clumps ?