Abstract
INFRA-RED STELLAR SPECTRA.—Some interesting experiments on the photography of stellar spectra in the extreme red have been made by Dr. P. W. Merrill, of the Bureau of Standards, Washington (Scientific Papers, No. 318). The actual tests were made at the Harvard College Observatory, where use was made of the 24-in. reflector, combined with objective prisms of different dispersions. The plates were sensitised for the red by staining with dicyanin, and pinaverdol was added when it was desired to photograph the yellow and green in addition. A large number of spectra of typical stars was obtained, with exposures ranging from 5 to 112 minutes, reaching in some cases as far as λ870, and showing the, atmospheric absorption bands B, a, and A. Several examples are reproduced, and it is clear that results of considerable value to astronomers and physicists may be obtained in the future by this method. Among other results of interest Dr. Merrill has found a new absorption band in the spectra of the M stars at wave-length 760, which he has proved by laboratory experiments to belong to the titanium-oxide series; in Mira there is possibly still another band between 810 and 820. In stars of class N new bands have been found at 692, 708, and 723, and these differ from the characteristic bands of carbon in degenerating towards the less refrangible part of the spectrum; it is suggested that they may possibly be due to cyanogen. The great contrast in energy distribution in the different classes of stars is very strongly emphasised by the extended range of observation, For classes B and A the blue portion is much the stronger; at class K the blue and red are about equal; while for classes M and N the red is the stronger.
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Our Astronomical Column . Nature 102, 13 (1918). https://doi.org/10.1038/102013a0
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DOI: https://doi.org/10.1038/102013a0