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The Birth of Stars
Birth of stars
Death of stars
What do we call the birthplace of stars?
Stellar Nursery: The Carina Nebula with the Hubble Telescope
What are we looking at?
Stellar Nursery: The Orion Nebula with the Hubble Space
Telescope
What are we looking at?
Where is the Orion Nebula?
Where is the Orion Nebula?
A slightly older nursery (middle school?): The Pleiades cluster
Age ~ 100 Myr. (Age of Orion Nebula ~1 Myr)
The Pleiades cluster is called “Subaru” in Japanese
and has importance in cultures all around the world
http://en.wikipedia.org/wiki/Pleiades_in_folklore_and_literature
Artist’s depiction of the Milky Way Galaxy
Credit:Lynette Cook
Simulations of stellar nurseries show how
these complex structures form
Orion Nebula seen with the
Hubble Space Telescope
What is the difference between an
“animation” and a “simulation”?
animation
simulation
What forces would a star-formation
simulation need to include?
What forces would a star-formation
simulation need to include?
-Gravity
-Pressure
-Magnetic fields
How do you design a computer
simulation?
How do you design a computer
simulation?
old positions
Calculation of forces
new positions
Let’s “zoom in” and think about a single
star forming out of a single small cloud
What force keeps a cloud from
collapsing?
Gas pressure pushes out, like in a balloon
What force might cause material in clouds to
collapse?
Gravity pulls material inwards
Clouds collapse to form stars when the force
of gravity is larger than the pressure force.
What type of cloud is more likely to collapse?
A.  A hot and small cloud
B.  A large and cold cloud
If a cloud is massive enough and cold enough,
it will begin to collapse.
The cloud is spinning.
What happens as it collapses?
(Think of the water in a drain, or a figure skater)
gravity pulls inwards
“Conservation of angular momentum”
(My definition: If spinning things get smaller, they
must spin faster)
What does “conservation” mean?
What does “momentum” mean?
What does “angular momentum” mean?
Let’s watch a video: angular_momentum.mp4
(00:24:00)
As a cloud collapses, it spins faster and faster
What happens to the cloud as it spins faster and
faster?
Physics major Louisa Barama shows off
her angular momentum!
What happens to the cloud as it spins faster and
faster?
Notice what’s happening to her skirt!
The cloud spins faster and faster, until it can’t
support itself, and flattens out partly into a disk
Think of the cloud as a figure skater, and the
disk as a skirt.
Lucky for us, this is the perfect way to form a
solar system.
disk = future solar system
blob = future sun
The disks that form around young stars are
called “protoplanetary disks”
disk = future solar system
blob = future sun
The formation of planets occurs at the same
time as the formation of stars
Can we observe these disks?
Orion Nebula
Orion Nebula: Close-ups reveal spinning disks around baby stars
“Protoplanetary disks”
What are we seeing in these images?
Artist’s Rendition of a protoplanetary disk
Credit: NASA, JPL-Caltech
Artist’s rendition of protoplanetary
disk
Diagram of orbits in the
solar system