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

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

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

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

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

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

Canterbury Massive O-Stars

Canterbury Massive OB-Stars

Canterbury OB-Stars + Dust

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

Canterbury The Circinus Cloud

Canterbury   B68

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

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

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

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

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

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

Canterbury Subaru Telescope Orion Nebula

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

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

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

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 )

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

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

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

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

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

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

Canterbury Now, how does it work?

Canterbury

Orion Nebula: Discs seen in silhouette

Canterbury

HH 46/47

Canterbury HH 212

Canterbury HH 46/47 HST

Canterbury HH 46/47 HST

Canterbury HH 34 HST

Canterbury HH 34 HST

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

Canterbury Planet Formation

Canterbury

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