Brightness Temperature of the Quiet Sun at Centimeter and Millimeter Wavelengths

Abstract

Brightness-temperature measurements of the quiet Sun are tabulated and plotted for the centimeter, millimeter, and infrared wavelengths. The plot gives an over-all picture of the chromosphere. The meas- urements at centimeter and millimeter wavelengths are compared with temperatures derived from two solar models. The reported brightness-temperature measurements show that a revision of chromospheric electron temperature and density estimates is needed and suggest the possibility of a temperature inver- sion in the chromosphere. The refinement of chromospheric models is dependent upon more accurate and higher-resolution measurements at millimeter wavelengths