Forming Planets

CEA Saclay simulation

New Worlds

How long does it take to make a solar system?

A. 1 million years.

B. 10 million years.

C. 100 million years.

D. 1 billion years.

Gases in Space

• Supernova stars explode and create clouds of gas and dust.

• The gas includes hydrogen, helium, nitrogen, oxygen, etc.

Crab Nebula, 1000 years old

Formation of the Sun

• Stars are formed by a gas/dust cloud contracting due to gravity.

Orion Nebula, 1 million years old

Protoplanetary Disk

• Gases begin to swirl around the star.– Inward from gravity

– Outward from heat

• Angular momentum is conserved.

HR 4796A,

10 million years old

Collisions and Accretion

• From 10 to 100 million years, dust begins to stick together.

• This is called accretion, and is aided by gravity.– Solid accretion toward star

– Gas accretion outward

Radio image of Epsilon Eridani,

500 million years old

Migration

• There is more gas and dust near the star for formation.

• A planet moving outward can slow the spin of a star.– Conservation of angular momentum

Protoplanet 6 MJ, 2 million years old

Keck telescope, 2011

Frost Line

• The heat of a star melts minerals that are close.

• Frozen “ices” dominate at greater distances.

U Hawaii