Half-hours with the Telescope - Being a Popular Guide to the Use of the Telescope as a - Means of Amusement and Instruction. by Richard Anthony Proctor
page 64 of 115 (55%)
page 64 of 115 (55%)
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since the distance between the components of [xi] has greatly diminished
of late. Both the components of [pi] are white, and their magnitudes are 3-1/2 and 6. We shall next turn to an exceedingly beautiful and delicate object, the double star [epsilon] Bootis, known also as Mirac and, on account of its extreme beauty, called Pulcherrima by Admiral Smyth. The components of this beautiful double are of the third and seventh magnitude, the primary orange, the secondary sea-green. The distance separating the components is about 3 seconds, perhaps more; it appears to have been slowly increasing during the past ten or twelve years. Smyth assigns to this system a period of revolution of 980 years, but there can be little doubt that the true period is largely in excess of this estimate. Observers in southern latitudes consider that the colours of the components are yellow and blue, not orange and green as most of our northern observers have estimated them. A little beyond the lower left-hand corner of the map is the star [delta] Serpentis, in the position shown in the Frontispiece, Map 3. This is the star which at the hour and season depicted in Map 2 formed the uppermost of a vertical row of stars, which has now assumed an almost horizontal position. The components of [delta] Serpentis are about 3-1/2 seconds apart, their magnitudes 3 and 5, both white. The stars [theta]^{1} and [theta]^{2} Serpentis form a wide double, the distance between the components being 21-1/2 seconds. They are nearly equal in magnitude, the primary being 4-1/2, the secondary 5. Both are yellow, the primary being of a paler yellow colour than the smaller star. But the observer may not know where to look for [theta] Serpentis, since it falls in a part of the constellation quite separated from that |
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