Page:Popular Science Monthly Volume 41.djvu/414

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in the present year, and still visible with an opera-glass. It lies about two degrees south of the star Chi Aurigæ, in the Milky Way, and when first noticed was about magnitude four and a half. The star seems to have been visible for some time previously, as it has been found that its spectrum was photographed at Harvard Observatory, U.S.A., on December 1st, 10th, and 20th, before it was recognized as a new star. The actual time of its appearance therefore remains unknown, but that it is a new star there can be no doubt, as it does not appear in any star-chart or catalogue. The star is a very interesting object, and, according to observations by the present writer, is subject to sudden changes of brightness. It seems to be fading slowly, and on March 1st was still somewhat brighter than the sixth magnitude.[1] Its spectrum is a very remarkable one, showing, it is thought, both bright and dark lines. The line C and other lines in the red are visible, the D line of sodium and the series of hydrogen lines being also present. Most of the lines are said to be double, each consisting of a bright and dark component. These double lines suggest the presence of two bodies, or systems of bodies, one approaching the eye and the other receding from it, with a relative velocity of between five hundred and six hundred miles per second. There is a suspicion that the bright lines characteristic of nebular spectra are also visible. These remarkable results suggest that the light of this star, and probably that of all "temporary" stars, is due either to the rush of a solid body through a gaseous nebula, or the clashing together of two meteoric swarms moving in opposite directions. The phenomenon might also be explained by two bodies forming a binary star passing through their perihelion, the great increase of light being due to a "violent grazing collision" at the point of nearest approach. Whether this new star is a veritable nova, or "temporary star," or merely represents the maximum of a hitherto unrecognized variable star of long period, like the so-called "Nova Orionis," discovered by the present writer in December, 1885, must be left to time to decide. In either case, it is a most interesting object, and its future career will be followed by astronomers with great interest.

Coming now to Class 2, we find regular variable stars with periods ranging from about 100 to 700 days, and with fluctuations in their light from about one magnitude to over eight magnitudes. Among the most remarkable of these are Mira Ceti, or the "wonderful star"; Chi Cygni, already referred to; R. Hy-

  1. Further observations on March 10th and 11th showed that the star had then faded to below the seventh magnitude; and on March 16th I could no longer see it through an opera-glass.