RADÓ KÖVESLIGETHY'S SPECTROSCOPIC WORK

Abstract

Kirchhoff and Bunsen's revolutionary discovery of spectral analysis in 1859 showed that observation of spectra made it possible to study the chemical composition of emitting bodies. Thermodynamics predicted the existence of black body radiation. The first successful spectral equation of black body radiation was the theory of continuous spectra of celestial bodies by Radó von Kövesligethy (published in 1885 in Hungarian, in 1890 in German). Kövesligethy made several assumptions on the matter-radiation interaction. Based on these assumptions, he derived a spectral equation with the following properties: the spectral distribution of radiation depended only on the temperature, the total irradiated energy was finite (fifteen years before Planck!) and the wavelength of the intensity maximum was inversely proportional to the temperature (eight years before Wien!). Using his spectral equation, he estimated the temperature of several celestial bodies, including the Sun. As a byproduct he developed a theory of spectroscopic instruments. He presented a comprehensive discussion on the quantitative relationship between astrophysical spectra and the observer, equipped with some kind of instrument (telescope, spectrograph, detector, etc.). We briefly summarize his main results.