The Birthplace of Stars

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The Birthplace of Stars
The space between the stars is not completely
empty. Thin clouds of hydrogen and helium, seeded
with the dust from dying stars, form in
interstellar space.
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Dark Clouds gather
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Molecular Clouds
Sometimes (especially in spiral arms), the gas is
compressed enough that the dust is thick and
gravity can collapse knots in these molecular
clouds to make new stars.
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The Initial Collapse
The center of the cloud is densest, so it
collapses first. Pressure is removed in an wave
moving out at the speed of sound. Material
free-falls inside this wave and crashes into a
growing (and glowing) central object. We see only
the infrared light emerging from the large dust
core.
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A little bit of spin goes a long way
Galactic shear and turbulence give every core a
little spin (once round in 10 million years). But
they get a lot smaller, and the spin goes up to
orbital! It is for this reason that we believe
there are many planetary systems it is part and
parcel of the star formation process to make a
disk. Typical Galactic spin makes disks about the
size of our Solar System
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The Sword of Orion
The nearest great stellar nursery to us is the
great Orion molecular cloud which is about 1000
light years away, and manufacturing thousands of
stars. This is probably how the typical star is
made.
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The glowing tip of a molecular cigar
The Orion nebula is powered by 4 high mass
luminous stars, which have cleared out their
birthplace and are eating at a long cloud pointed
at us.
The Trapezium
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Nearby, lower mass stars are forming
Hubble Space Telescope
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They look like little windsocks
The blast from the luminous stars is eating away
at the little guys
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The heart of them contains a potential new solar
system
Proplyds are new star-disk systems
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With powerful bipolar jets
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The Star-Disk System Forms while infall continues
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Jets remove excess angular momentum
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In the center - T Tauri Stars
The new young star is exposed, while the
accretion disk is still in place. The spectrum of
all is seen together (so we dont have to image
disks in order to know they are there).
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Half the time, two (or more) stars form
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Most stars form in clusters
The typical cluster doesnt stay bound once the
stars form. The remaining 80-90 of the gas
dissipates and the stars drift apart.
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Star Formation is Beautiful, but ephemeral
Within about 10 million years, the birth-cloud is
shredded, and the disks are dissipated. The
process of starbirth has ended.
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The stage is set for planet formation