PX282 - G4 - solar atmosphere

image: NASA

• the corona, which is the extended atmosphere, is visible during an eclipse
• light scattering off free electrons in the extended atmosphere

image: NASA SDO

• in optics, the photosphere is seen, where the sun transitions from optically thick (opaque) to optically thin (transparent)
• in extreme UV, $\gamma$ and x-rays, the extended emission from hot plasma is seen

image: carroll & ostile (2007)

• temperature inversion in the solar atmosphere of up to $-{10}^{6}K$

• the heating is related to the magnetic field, but the mechanism is poorly understood

• x-ray spectrum emission lines, dominated by excitation due to collisions

• show optically thin thermal emission from a hot plasma

• in the corona, the plasma is confined to many magnetic field loops by the the lorentz force