Open AccessSolar radiation in the radio spectrum - I. Radiation from the quiet sun
Author(s) -
D F MARTYN
Publication year - 1948
Publication title -
proceedings of the royal society of london. series a, mathematical and physical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.814
H-Index - 135
eISSN - 2053-9169
pISSN - 0080-4630
DOI - 10.1098/rspa.1948.0032
Subject(s) - physics , radio wave , envelope (radar) , radiation , astrophysics , computational physics , absorption (acoustics) , optics , quantum mechanics , telecommunications , radar , computer science
The theory of the emission of thermal radiation from the solar envelope at radio-frequencies is worked out in detail. The Lorentz theory of absorption is used in conjunction with Kirchhoff’s law to derive the effective temperature of the various regions of the solar disk over the radio spectrum. A maximum effective temperature approaching 106 °C is found in the vicinity of 1 m. wave-length. Limb brightening occurs at centimetre wave-lengths. It is shown that Gaunt’s quantum mechanical expression for free-free emission yields results almost identical with the classical treatment, provided Chapman and Cowling’s expression for the collision frequency in a fully ionized gas is used in the latter treatment. It is suggested that it may be preferable to treat problems of solar and galactic radio noise by classical methods, particularly when the refractive index of the medium departs appreciably from unity.