1. Star Formation in our Galaxy Dr Andrew Walsh (James Cook University, Australia) Lecture 1 – Introduction to Star Formation Throughout the Galaxy Lecture 2 – Chemistry and Star Formation Lecture 3 – High Mass Star Formation and Masers Lecture 4 – G305.2+0.2: A Case Study and Galactic Plane Surveys

2. Star Formation in our Galaxy Introduction to Star Formation Throughout the Galaxy 1.Why study star formation? 2.The Galactic ecology 3.Dark clouds, complexes and giant molecular clouds 4.The Milky Way at different wavelengths 5.Young stellar object classes 6.Disks, jets and outflows 7.Gravitational collapse 8.Clustered star formation

3. Why Study Star Formation? Star formation is the process that determines the properties of the major building blocks of the universe: Stars, Planets and Galaxies

4. Why Study Star Formation? The birth of stars is the most poorly understood stage of evolution of stars Star formation is one of the most beautiful processes in the cosmos!

5. McCaughrean et al. 1996

6. The Galactic Ecology Supernova Molecular Cloud Cores Young stellar objects Stars High mass Low mass Planetary nebula White dwarf Neutron star Black hole Triggering SN shocks HMS winds Outflows

7. Cores, Dark clouds, Complexes and Giant Molecular Clouds Giant Molecular Clouds: ~10 5 solar masses ~50pc

8. Cores, Dark clouds, Complexes and Giant Molecular Clouds Dark Cloud Complexes: ~10 4 solar masses ~10pc

9. Cores, Dark clouds, Complexes and Giant Molecular Clouds

10. NH 3 (1,1) Dark Clouds

11. Optical Near-Infrared Masses: Between fractions and a few x 10 solar masses Sizes: ~1pc

12. Interstellar Extinction Red light is absorbed by dust less than blue light We can see deeper into dust-enshrouded objects at longer wavelengths. Extinction ~ λ -1.7

13. Dark Clouds 1.2 mm Dust Continuum C 18 O N 2 H + Optical Near-Infrared Masses: Between fractions and a few x 10 solar masses Sizes: ~1pc

14. Properties of Cores, Dark clouds, Complexes and Giant Molecular Clouds Type n Size T Mass [cm -3 ] [pc] [K] [M sun ] Giant Molecular Cloud 10 2 50 15 10 5 Dark Cloud Complex 5x10 2 10 10 10 4 Individual Dark Cloud 10 3 2 10 30 Dense low-mass cores 10 4 0.1 10 10 Dense high-mass cores >10 5 0.1-1 10-30 100-1000

16. Planck's Black Body

18. Wien's Law max = 2.9/T [mm] Examples: The Sun T  6000 K  max = 480 nm (optical) Humans T  310 K  max = 9.4  m (MIR) Molecular Clouds T  20 K  max = 145  m (FIR) Cosmic Background T  2.7 K  max = 1.1 mm (mm)

20. Spectral Energy Distribution

21. Class 0, I, II and III Young Stellar Objects

22. McCaughrean et al. 1996

24. Discovery of outflows Herbig 1950, 1951; Haro 1952, 1953 Initially thought to be embedded protostars but soon spectra were recognized as caused by shock waves --> jets and outflows

25. Discovery of outflows - In the mid to late 70th, first CO non-Gaussian line wing emission detected (Kwan & Scovile 1976). - Bipolar structures, extremely energetic, often associated with HH objects Bachiller et al. 1990 Snell et al. 1980

26. The prototypical molecular outflow HH211

27. General outflow properties - Jet velocities 100-500 km/s Outflow velocities 10-50 km/s - Estimated dynamical ages between 10 3 and 10 5 years - Size between 0.1 and 1 pc - Force provided by stellar radiation too low (middle panel) --> non-radiative processes necessary! Mass vs. L Force vs. L Outflow rate vs. L Wu et al. 2004, 2005

28. Snell et al. 1980 Spectral Line Profiles Outflow wings Infall

29. 1.Rising T ex along line of sight 2.Velocity gradient 3.Line optically thick 4.An additional optically thin line peaks at center Spectral Line Profiles Outflow wings Infall

30. Infall Profiles HCO+ (1-0) Optically thick N2H+ (1-0) Optically thin Walsh et al. 2006

31. Infall Profiles Walsh et al. 2006

32. Clustered Star Formation

33. Most stars are formed in clusters (Maybe) ALL High Mass Stars Formed in Clusters

34. Spitzer 3-colour image of NGC 1333 - Courtesy Rob Gutermuth (CfA)

37. Clustered Star Formation Walsh et al. 2007 Red & Blue = HCO + (1-0) Greyscale = N 2 H + (1-0) + = dust continuum cores

38. Clustered Star Formation