Absolute Spectral Energy Distributions in Stars

Abstract

The importance of measuring absolute energy distributions of stars was realized more than thirty years ago. At that time the main emphasis was on the comparison of fluxes from stars with those from suitable black-body sources on the Earth. In Germany extensive work of this kind was carried out by Kienle (1); Kienle, Strassl & Wempe (2); and Kienle, Wempe & Beileke (3). In England work was done at Greenwich by Dyson et al. (4), and by Greaves, Davidson & Martin (5). Williams (6, 7, 8), and Hall (9, 10, 11) did similar work in the United States. In France the early work was by Arnulf et al. (12). This work, apart from that of Hall, was all done by photographic techniques which were very difficult because of the large range in intensity which had to be covered and the difficulty of making accurate plate calibrations. There have been many comparisons of the results of these workers, the most recent one being that of Code (13). The importance of this work has been discussed and emphasized by Kienle (14), Barbier & Chalonge (15, 16), and Unsold (17). During the last ten years techniques for computing accurate model atmospheres have improved greatly and theoretical emergent fluxes are now available for stars of almost all temperatures and gravities. This development has again emphasized the need both for accurate absolute calibration of the fluxes from stars and for data on large numbers of stars.

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