Transcript The Birth of Stars - University of California, Berkeley

The Birth of Solar Systems
Formation of a protostar and disk
Collapse of
and
interstellar
cloud
The disk condenses and dissipates
A solar system
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.
Hot Stars make their Nurseries glow
The Orion Region
Infrared
Optical
Dark Clouds
gather
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.
Where Stars Begin
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…
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.
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
Near them, lower mass stars are forming
Hubble Space Telescope
They look like little windsocks
The blast from the luminous stars is eating away at the little guys
The heart of them contains a potential new solar system
“Proplyds” are new star-disk systems
Orion Proplyds
A whole cluster of new stars is born before us
Hundreds of young stars, often with disks, have been seen.
Disks in Orion
Orion in the near infrared
The Star-Disk System Forms
And emits powerful bipolar jets
which extend for
many light years
negative image
The jet shocks are called Herbig-Haro Objects
Orion A
The jet is powered by
the stellar magnetic
field and rotation, and
takes away excess
angular momentum
piercing back out into the cloud
T Tauri Stars
The Young Star is Very Active
The magnetic flux is
hundreds of times
stronger than the Sun,
and huge starspots are
seen. The star itself is 3
times bigger.
The stage is set for planet formation
We see remnant disks around other stars
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.