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Transcript
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