Orion Nebula: Star-forming Region. Solar Nebula. Flattening the Solar Nebula. Disks Around Other Stars. Steps in Planet Formation. Condensation Accretion Nebular Capture (Jovian Planets only) After planets form, the solar wind clears the nebula: gas and dust are blown away.
Steps in Planet Formation • Condensation • Accretion • Nebular Capture (Jovian Planets only) • After planets form, the solar wind clears the nebula: gas and dust are blown away
Condensation and Temperature • Metals: iron, nickel, aluminum, and other metals can solidify around 1600 K • Rocks: primarily silicon-based minerals solidify around 500-1300 K • Hydrogen Compounds: molecules of methane, ammonia, and water freeze into ices below 150 K • Light gases: hydrogen and helium never condense in the solar nebula
Accretion into Planetesimals • Condensed materials collide and stick together forming planetesimals • Planetesimals would continue to grow from further accretion and gravity • Larger planetesimals would form spherical shapes because of stronger self-gravity • Some planetesimals would fragment due to collisions
Nebular Capture: Jovian Planets • Larger planetesimals of the Jovian planets resulting in a stronger gravitational force • Stronger gravity allowed the Jovian plantes to capture more gas and planetesimals • Hydrogen and Helium gas could be captured despite low mass of these gases • Jovian planets formed disk-shaped nebulae • Lower temperatures meant Hydrogen and Helium gas would not escape from the Jovian planets
The Sun’s Lost Spin • Magnetic field of the Sun drags charged particles in the disk of the solar nebula. • This causes friction which slows down the rotation of the Sun • Otherwise, the Sun should have a faster spin than is observed
First Direct Detection! • Planet Orbiting the star HD209548 • Eclipsed by planet