orion nebula: star-forming region. solar nebula flattening the solar nebula
Post on 20-Dec-2015
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Orion Nebula: Star-forming Region
Solar Nebula
Flattening the Solar Nebula
Disks Around Other Stars
Steps in Planet Formation
1. Condensation
2. Accretion
3. 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
Planetesimals to Planets
Self-gravity
Uncompressed Densities
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
Nebular Capture: 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
A History of Impacts
Captured Moons of Mars
Leftover Planetesimals
Radioactive Dating
Detecting Extrasolar Planets
Detecting Extrasolar Planets
Extrasolar Planets
More Extrasolar Planets
First Direct Detection!
• Planet Orbiting the star HD209548
• Eclipsed by planet
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