Lecture 22 Star Formation from Molecular Clouds

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Lecture 22 - Star Formation from Molecular Clouds

• Gravitational contraction of gas clumps (like
  balloons) cant happen in the atmosphere because
  you cant get as big as the Jeans Length. But in
  interstellar space, its a different story

Term the Interstellar Medium- material in space
between the stars
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A Star is born.
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A Star is born (Part 2)
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Forming stars eventually rip up the molecular
cloud in which they formed. The molecular cloud
is dissipated after about 30 million years. (How
can we know that?)
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Star formation and the conservation of angular
momentum
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You can see these phenomena in stars in the sky
(T Tauri stars, Herbig-Haro objects, etc)
jet
Accretion disk
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Question

• We see these processes occurring in young
  protostars.
• We understand the physics of these processes (at
  least partially)
• We believe the Sun formed like this.
• What characteristic of the solar system can we
  see that is an indicator of the processes of
  contraction, jet formation, accretion disk
  formation, etc?

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Young Stars with Accretion Disks
Beta Pictoris
Fomalhaut
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Artists Conception of Fomalhaut System
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Summary of what we know about the formation of
stars

• Stars form from the massive amounts of material
  in cold, dark molecular clouds
• Contraction from the low density molecular cloud
  to a dense, compact, shining star occurs through
  gravitational contraction (Jeans Length)
• As the star contracts and spins up, it sheds a
  disk of matter, from which planets form.

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Where do we see this occurring?

• Everywhere in the sky. Particularly in the Milky
  Way. Check the Skalnate Pleso charts for Taurus
  and Auriga