Parallels: Proto-Planetary Disks and rings

1. Parallels: Proto-Planetary Disks and rings 30 November 2015

2. Origin of the Solar System • It’s a fundamental problem in astronomy • We must explain the characteristics of our own system, and of planets around other stars • Elements were made inside stars • Stars formed from giant molecular clouds • Planets form in a disk around the protostar • Giant planets form from accretion onto cores • Terrestrial planets are only the cores

5. Characteristics of our Solar System • Regular planet orbits • Planets are closely spaced • Terrestrial and Jovian planets • Asteroids and comets leftover • Satellites and rings imitate a miniature Solar System

6. Stages in planet formation • Dust collects in the mid-plane of the protoplanetary disk • Grows by mutual collisions: ‘accretion’ • Planetesimals (about 1km across) grow and collide • Giant collisions are the final stage • Giant planet cores are bigger outside the frost-line: they attract gas to become gas giants like Jupiter • Star ignites: the gas and dust blown away

8. Leftovers • Near the Sun (inside frost-line, also known as snow line or ice line) rocky objects become asteroids • Far from the Sun (outside frost-line) icy objects form the comets and Kuiper Belt Objects

9. Density waves and propellers in a forming disk