Comets
Comets a direct link to formation of Solar System
- remnant material from 4.6 billion y. ago
Indirectly, we observe nearby examples of recent star formation
- Laws of physics the same
- Chemical composition the same
- Expect similar evolution
- Dust and gas disks common around very young stars
- IRAS satellite detected infrared from dust disk
- CO tracer gas molecule detected in Keplerian rotation
- Structure in disk suggests orbiting planets
- gaps HD 141569 disk, cleared inner region HR 4796 disk vg
- either planet cleared, or orbital resonance
- gaps would be filled in without planetary influence
- Orbiting planets affect the primitive bodies (planetesimals)