Transcript Lecture 22 - Star Formation from Molecular Clouds

Lecture 22 - Star Formation from
Molecular Clouds
Gravitational contraction of gas
clumps (like balloons) can’t happen
in the atmosphere because you can’t
get as big as the Jeans Length. But in
interstellar space, it’s a different story
Term: the Interstellar Medium- material in space
between the stars
A Star is born….
A Star is born (Part 2) …
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?)
Star formation and the conservation
of angular momentum
You can see these
phenomena in stars in the
sky (T Tauri stars, HerbigHaro objects, etc)
jet
Accretion disk
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?
Young Stars with Accretion Disks
Beta Pictoris
Fomalhaut
Artist’s Conception of Fomalhaut
System
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.
Where do we see this occurring?
Everywhere in the sky. Particularly in
the Milky Way. Check the Skalnate
Pleso charts for Taurus and Auriga