June 1966: ex-variable star?
"[An] astonishing report by two Canadian astronomers, Serge Demers and J. D. Fernie of David Dunlap Observatory, [states] that a very well-known Cepheid variable star, RU Camelopardalis, has recently ceased to pulsate and now appears to be practically constant in brightness! ...
"These observations were carefully made, and no explanation in terms of a misidentified star or instrumental fault is possible.... According to the two Canadian astronomers, ... 'the pulsation has indeed died away. [For the star] to accomplish this in only four years is most remarkable, since simple theory (Eddington, 1926) would indicate a required time-scale of the order of [10.sup.3] to [10.sup.4] years."'
Soon, however, RU Cam was again pulsating. The star is now classified as a Cepheid of the W Virginis type, with light curves prone to unexpected changes in amplitude or period. These stars are much less luminous than the better-behaved Cepheids that astronomers use as intergalactic distance gauges.
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|Title Annotation:||75, 50 & 25 Years Ago; RU Camelopardalis|
|Author:||Sinnott, Roger W.|
|Publication:||Sky & Telescope|
|Article Type:||Brief article|
|Date:||Jun 1, 2016|
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