Abstract
THE BINARY STAR δ EQUULEI.—Mr. Burnham publishes a new epoch for this star, which there is now good reason to conclude will prove to be the most rapid revolver amongst the binary systems; on this account it well deserves the attention which Mr. Burnham claims for it at the hands of those observers who are in possession of instruments competent to cope with so close a double-star. The duplicity was detected by M. Otto Struve on August 19, 1852, with the Pulkowa refractor, when definition was unusually good, and the components almost equal in magnitude were “à peine séparées par une ligne noire.” In 1853 and 1854 it appeared single in the same instrument. The object was elongated in the summer of 1857, and at the date 1858–59 M. Struve saw the stars separated at moments, and they were again divided in the autumn of 1874. As is pointed out in the Pulkowa Observations, vol. ix., the case is evidently a similar one to that of 42 Comae Beren., the visualray coinciding very nearly with the plane of the orbit, so that the companion appears to oscillate backwards and forwards almost in a right line, and that of very small extent. M. Struve has established the period of revolution of 42 Comae to be only about twenty-five years, but δ Equulei appears to indicate a period of only thirteen or fourteen years. Mr. Burnham finds from five nights measures with the 18½inch Chicago refractor, 1880.60, Position 29°.1, Distance 0″.35.
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Our Astronomical Column . Nature 22, 593–594 (1880). https://doi.org/10.1038/022593a0
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DOI: https://doi.org/10.1038/022593a0