AST101H1 Lecture Notes - Lecture 6: Thermostat, Caffeine, Photon

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

Composition: 70% hydrogen, 28% helium, 1% oxygen, 0. 4% carbon, 0. 6% heavier elements. Light and heat travel outward from the core. Lots of churning: hot gas rising, cool gas falling. Granules approx 1000 km across, late 5-10 minutes. Seen only during total eclipse of the sun. So much fainter than the sun that it is basically invisible. Need to shrink by 25 metres/year, shine for 15 million years. Ex: 6 = 6 carbon, 26 = iron, 79 = gold, helium = 2. Electrons in atoms or molecules change over to new partners (nuclei just observe) Protons fiercely repel unless they get very close. At 15 million c, atoms moving so fast that they stick. When a nuclear reaction produces energy, that energy comes from converting mass into energy. Sun"s mass decreases every second by 4 tonnes - mass being converted. Chances of four particles crashing simultaneously is tiny. Each photon of light travels approx 0. 1mm before being randomly deflected.