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Canterbury 01.09.2014 The problem of star formation is not how to make stars. The problem of star formation is how not to make stars.

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Presentation on theme: "Canterbury 01.09.2014 The problem of star formation is not how to make stars. The problem of star formation is how not to make stars."— Presentation transcript:

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

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

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

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

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

6 Canterbury The Sky Gal. CenterGal. Plane Gal. North Pole Gal. South Pole

7 Canterbury Massive O-Stars

8 Canterbury Massive OB-Stars

9 Canterbury OB-Stars + Dust

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

11 Canterbury The Circinus Cloud

12 Canterbury   B68

13 Canterbury 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 Content

14 Canterbury Where do stars form? - in or near Giant Molecular Clouds mostly molecular hydrogen + 1% dust + traces of CO, H 2 O, NH 3,... - these clouds are massive ( M SUN ) - these clouds are cold (10-30K) Content

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

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

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

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

19 Canterbury Subaru Telescope Orion Nebula

20 Canterbury 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 Content

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

22 Canterbury OriB OriA  Ori Betelgeuse ONC NGC2024 NGC2071 MON R2 The Problem: 10s of light years

23 Canterbury The Problem: OriB OriA  Ori Betelgeuse ONC NGC2024 NGC2071 MON R2 10s of light years Solar Diameter Size: m  10 9 m 7 orders of magnitude(x ) Density: changes by 21 orders of magnitude (x )

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

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

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

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

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

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

30 Canterbury Now, how does it work?

31 Canterbury

32 Orion Nebula: Discs seen in silhouette

33 Canterbury

34 HH 46/47

35 Canterbury HH 212

36 Canterbury HH 46/47 HST

37 Canterbury HH 46/47 HST

38 Canterbury HH 34 HST

39 Canterbury HH 34 HST

40 Canterbury The Problem: OriB OriA  Ori Betelgeuse ONC NGC2024 NGC2071 MON R2 10s of light years Solar Diameter Gravity 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

41 Canterbury Planet Formation

42 Canterbury

43 The end


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