Magnetic fields -- sunspots
Most obvious effect of solar B fields are sunspots
- Outer layers of sun, convective energy transport W 21
- Like heat rising over a radiator
- hot air rises
- carries energy upwards
- deposits its energy and cools
- cool air falls
- to be re-heated, pick up more energy
- circulation transports energy from hotter region to cooler
- solar convection visible in “granulation” pattern seen in photosphere
- bright centers are rising hot gas
- dark borders are falling cool gas
- very strong B-field inhibits convection
- charged particles can’t cross B-field lines
- less energy transport leads to lower temperatures (4000 K)