Abstract
THE HERSCHELIAN COMPANION OF ALDEBARAN.—In a communication lately received from M. Camille Flam-marion, it is endeavoured to show that the change of relative situation of the small star with respect to Alde-baran, is not accounted for by the proper motion of the latter, as was stated by Struve (“Positiones Mediæ,” p. ccxxvi.), but that it is necessary to admit the existence of a very appreciable proper motion of the companion, which would be the first instance of the kind in so small a star. M. Flammarion collects the various published measures and adds to them measures made by Mr. Gled-hill in 1876, and by himself in 1877. Sir W. Herschel's measures may be set aside at once as not sufficiently exact for a discussion of a moderate proper motion; his angle in 1781 is the result of a siogle measure, and his distances, as is well known, are in defect, when they exceed a minute. Taking then Struve's epoch, 1836.06, as the earliest reliable datum we possess, and bringing it up to Dembowski's epoch, 1863.37, with Leverrier's proper motion for Aldebaran, we find no greater difference than may be accounted for by unavoidable error of observation, so that Struve's inference on comparing the Pulkowa measures, in 1851 with the Dorpat measures of 1836, “itaque comes motus non est particeps, sed in cœlo quiesca videtur,” and Dembowski's conclusion when speaking of this object and of λ Aurigae,” “Les differences s'accordent assez bien avec les mouvements propres des deux principales,” are thus supported. The angle, however, should now be less than is assigned by Mr. Gledhill and M. Flammarion from their own measures (35°.5), and further careful measures will be desirable to clear up a possible question of personal equation. If we reduce Struve's angle for 1836 with Leverrier's proper motion of Aldebaran to the present year, we find an angle nearer 32°.5 than 35°.5.
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Our Astronomical Column . Nature 16, 266–267 (1877). https://doi.org/10.1038/016266f0
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DOI: https://doi.org/10.1038/016266f0