AS 101: BIRTH OF SOLAR SYSTEM
In the beginning…
Young, newlyformed stars do not exist in isolation,
Always within cloud of gas
Often close to other young stars
Start with a cloud of gas (Solar Nebula)
4.5 billion years ago
Approx. 1 light year across (100x larger than solar system)
Spherical, cold, low density
Nurseries: Groups of young stars forming inside clouds of gas and
dust. ** Infrared observations are key.
Cloud of gas:
Gravity – cloud collapses inwards
Conservation of energy means gas gets hotter
Conservation of angular momentum
Cloud spins faster
As collapses it spins faster & gets smaller (scrunches inwards)
Conservation of momentum means:
Clouds get flatter, forming a disk
Orbits of gas molecules become more circular.
The protoplanetary disk:
Hot, spinning, flat cloud of gas results from the collapse of the solar nebula.
About 200 AU in diameter
Theory supported by observation of young stars supported by disks of gas.
Also by lots of infrared emission from these disks of gas.