Abstract
THE COLOURS OF α URSÆ MAJORIS AND ARCTURUS.—Mr. T. W. Backhouse, writing with reference to the periodical change of colour in α Ursæ Majoris, indicated by the observations of Herr Weber, of Peckoloh, of which mention was made recently in this column, remarks that after watching it for several months he concludes the variation must be very slight. Mr. Backhouse observed with a small binocular, power 21/2, with which he estimated the depth of colour as compared with β Ursæ Majoris and β Ursæ Minoris, which are respectively bluish and deep orange, not the actual colour of the star. Representing the difference between the two stars of comparison by a scale from 0 to 1, “sthe depth of colour of a Ursæ Majoris only varied from 4/7 to 3/4 on this scale, so that the whole range of its variations was less than 1/5 of the difference between those two stars, probably not greater than can be accounted for by errors of observation. The greatest depth of colour, assuming β Urs. Maj. and β Urs. Min. not to vary, was observed on January 6, March. 18, and April 11, which are not long after Weber's times of minimum.” Mr. Backhouse adds that if any period is indicated by his observations, it is more likely to be one of three months than any other.
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Our Astronomical Column . Nature 16, 330 (1877). https://doi.org/10.1038/016330a0
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DOI: https://doi.org/10.1038/016330a0