PANNEKOEK’S GALAXY

Abstract

Antonie ('Anton') Pannekoek (1873Pannekoek ( -1960, the founder of the Astronomical Institute of the University of Amsterdam, is remembered as one of the initiators of the field of stellar atmospheres. A second, maybe equally significant part of his research and legacy did not concern stellar, but Galactic astronomy. He was awarded an honorary doctorate by Harvard University and the Gold Medal of the Royal Astronomical Society (UK) for his total research effort. From his long-term interest in viewing and mapping the Milky Way he became convinced that the sidereal system was built up of clouds of stars, condensations of various sizes in a smooth but low-density stratum of stars. In addition, there were dark clouds together with streaks with little or no extinction in between them. So, he took the opposite view of Jacobus C. Kapteyn, concerning the stellar distribution, which the latter regarded in first approximation to be smooth and uniform in longitude so that star counts as a function of apparent magnitude depended primarily on latitude. Pannekoek's research into the structure of the stellar system consisted of various parts.