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The problem of star formation is not how to make stars.

The problem of star formation is not how to make stars. The problem of star formation is how not to make stars. The Physics of Star Formation. Dr Dirk Froebrich University of Kent. Content. - How do we know stars are forming? - Where do stars form? - Properties of young stars

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The problem of star formation is not how to make stars.

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  1. The problem of star formation is not how to make stars. The problem of star formation is how not to make stars.

  2. The Physics of Star Formation Dr Dirk Froebrich University of Kent

  3. Content - How do we know stars are forming? - Where do stars form? - Properties of young stars - Temperature & Turbulence vs. Gravity - Collapse, Discs and Jets

  4. Content - How do we know stars are forming? - Where do stars form? - Properties of young stars - Temperature & Turbulence vs. Gravity - Collapse, Discs and Jets

  5. Inside Stars... Massive stars are bright and short lived (few Million years)

  6. The Sky Gal. North Pole Gal. Plane Gal. Center Gal. Plane Gal. South Pole

  7. Massive O-Stars

  8. Massive OB-Stars

  9. OB-Stars + Dust

  10. OB-Stars + Dust Gal. North Pole Gal. Plane Gal. Center Gal. Plane Gal. South Pole

  11. The Circinus Cloud

  12. B68 k  lb

  13. Content - How do we know stars are forming? - short lived massive stars exist - they must have formed in the last few Myrs - the Universe is 13.7Gyrs old

  14. Content - Where do stars form? - in or near Giant Molecular Clouds mostly molecular hydrogen + 1% dust + traces of CO, H2O, NH3, ... - these clouds are massive (104-106MSUN) - these clouds are cold (10-30K)

  15. Content - How do we know stars are forming? - Where do stars form? - Properties of young stars - Temperature & Turbulence vs. Gravity - Collapse, Discs and Jets

  16. Region S106: 150 young stars forming in Cygnus Subaru Observatory

  17. Hubble Space Telescope Region NGC346: young stars forming in the LMC

  18. Hubble Space Telescope Tarantula Nebula: young stars forming in the LMC

  19. Orion Nebula Subaru Telescope

  20. Content - Properties of young stars - they are ‘social‘ – most form in clusters, some in isolation - single/binary/tripple/multiple – 147/64/9/1 - many low mass and few high mass stars, universal mass distribution

  21. Content - How do we know stars are forming? - Where do stars form? - Properties of young stars - Temperature & Turbulence vs. Gravity - Collapse, Discs and Jets

  22. The Problem: Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB

  23. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Solar Diameter Size: 1016m  109m 7 orders of magnitude (x 10.000.000) Density: changes by 21 orders of magnitude (x 1.000.000.000.000.000.000.000)

  24. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Gravity Solar Diameter But why has not everything collapsed? Thermal Pressure of gas clouds  critical (Jeans) mass for collapse about 1MSUN for a cloud of 1ly radius

  25. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Gravity Solar Diameter Gravity vs. Thermal pressure Almost all clouds are above Jeans limit  should collapse  But we do not observe this! Solution: Turbulence

  26. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Gravity Solar Diameter Turbulence: random bulk motion of material at supersonic velocities v>sound speed (200m/s) creation of shocks increasing density

  27. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Gravity Solar Diameter Gravity vs. Thermal pressure + Turbulence Star Formation is the interplay of Gravity and supersonic turbulence in Molecular Clouds  Gravoturbulent Fragmentation

  28. Content - How do we know stars are forming? - Where do stars form? - Properties of young stars - Temperature & Turbulence vs. Gravity - Collapse, Discs and Jets

  29. Stage 1 Stage 2 Stage 3 Now, how does it work?

  30. Now, how does it work?

  31. Orion Nebula: Discs seen in silhouette

  32. HH 46/47

  33. HH 212

  34. HH 46/47 HST 1994 - 1997

  35. HH 46/47 HST 1994 - 1997

  36. HH 34 HST 1994 - 1997

  37. HH 34 HST 1994 - 1997

  38. Betelgeuse MON R2 l-Ori NGC2071 OriA NGC2024 ONC 10s of light years OriB The Problem: Gravity Solar Diameter Gravity vs. Thermal Pressure + Turbulence + angular Momentum + magn. Fields Spin  accretion disc formation  ejection of jets (accelerated and collimated by magnetic fields)  feedback from outflows and radiation  turblence

  39. Planet Formation

  40. The end

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