The Birth of Solar Systems A solar system The disk condenses and dissipates Collapse of and interstellar cloud Formation of a protostar and disk

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 Orion in the near infrared Disks in Orion Hundreds of young stars, often with disks, have been seen.

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.