|
|
Magnetic Fields Earth B = 1 gauss Energy Density = 1/8p = 0.4 ergs cm-3 For comparison: P=nkT ~ 1019 * 1.4 * 10-16 * 300 = 4 * 105 erg cm-3 Why the Earths B field does no affect us. In Sun T = 6000 at surface If B2/8p = 10-3P : significant effects B2 ~ 109 B ~ 3*104 gauss Happens in Sun corona How does field get this high?
Rotation winds up B field lines Differential rotation Equator 25d period Latitude = 40 27d period Flux tube twisted: gets twisted like a rope, B density increases until it buoys local gas up and makes tube above surface.
Chromosphere Lower down and cooler. Heated by shock waves?
Magnetic Recombination
Corona 2 * 10^6 K in loops Luminosity = 10^-6 Lsun = 4* 10^27 erg sec^-1 Heating mechanism unknown |