• Gyroresonance
opacity is the only mechanism capable of
making the corona optically thick at
frequencies above 4 GHz
•Emission comes from a
surface of constant magnetic field in the
corona
• Coronal temperatures indicate the
presence of magnetic field strengths
at appropriate strengths: microwaves
are sensitive to fields in the range
200–3000 G.
• High levels of circular polarization also indicate presence of strong magnetic fields and can be used to measure temperature gradients
Gyroresonance
layers