Notes Pratiques sur l'Observation Visuelle des Etoiles Variables

Abstract

THE careful and persistent observation of variable stars has risen from being the occasional hobby of a few observers to one of the most important branches of stellar physics, from which far-reaching deductions have been drawn concerning star-life, absolute magnitudes, and the structure of the universe. The number of variables is now so large that a considerable army of workers is required. The author's aim is to enlist recruits, and the field of work that he recommends is that of the long-period variables of large light-range, since visual estimates of light-difference are sufficient in these, while the Cepheids and eclipse-variables call for more refined methods and more highly trained observers. The use of charts for identifying the variable and comparison stars is explained, also the “fraction” and “step” methods of estimating light-intervals, the drawing of the light-curve, and the deduction of the epochs of maximum and minimum. The amateur who contemplates extensive work in this field is wisely recommended to join the variable star section of the British Astronomical Association; its director makes a selection of the stars needing observation, and divides the work among its members.

Notes Pratiques sur l'Observation Visuelle des Etoiles Variables.

Par Maurice E. J. Gheury de Bray. Extrait de Ciel et Terre. (Published by the Author: 40 Westmount Road, Eltham, S.E.9.) Price 2s. 4d. post free.