It is proposed to discuss the role of the radio-frequency emission in the whole set of the non-thermal emissions of the sun, which originate in the solar corona and the uppermost regions of the chromosphere. Of these, the radiative emissions give probably an amount of between 104and 105ergs/cm.2sec., to which the radio-frequency region contributes only very little (even during an intense outburst, when the total radiative emission is much larger, not more than 10°–102ergs/cm.2sec.); the contribution of the lower chromosphere, however, is not yet well known. The corpuscular emissions under normal conditions seem to require ≈ 105ergs/cm.2sec. (but again much more in active, e.g. ‘M’, regions), and to constitute a normal feature of the outer solar corona. These emissions, we propose, are maintained by the same supply of mechanical energy which secures the thermal and radiative equilibrium of the inner corona. That is to say, some part of the flux of acoustic energy originating in the hydrogen convection zone and, according to this theory, heating the upper chromosphere and the inner corona, is believed always to reach the outer corona, where the radiative loss is smaller, and this part is then at least comparable with that dissipated in the inner corona.*
Spacecraft Radio Frequency Fluctuations in the Solar Corona: A MESSENGER–HELIOS Composite Study
