Our Astronomical Column

Abstract

STARS WITH REMARKABLE SPECTRA.—At those stages of celestial evolution in which the temperature is low, it is probable that the average condensing body will not be very bright, so that the study of their spectra at these phases of their development presents some difficulties. Thus, the great majority of the stars with bright-line spectra, and stars showing intense carbon absorption, are of low magnitudes, and because comparatively few were identified in the earlier surveys of stellar spectra, they were looked upon as “peculiar.” Nevertheless, a study of these spectra in relation to those of the brighter stars indicated that they probably represented stages in the history of all condensing bodies, so that their discovery in greater numbers was only to be expected. At Harvard College especially has the photographic investigation of these faint spectra been carried on, and the discovery of eleven more objects with peculiar spectra has been recently announced by Mrs. Fleming; two of these are simply stated to be “peculiar,” three are nebulas with bright lines, two have the F line of hydrogen bright, two appear to be bright-line stars of the Wolf-Rayet type, and two show carbon absorption. In addition, the spectra of eleven stars of the α Herculis type were found to show the F line of hydrogen bright, and this unfailing sign of variability in this group of stars is fully substantiated by an examination of chart plates of the same regions (Astrophysteal Journal, May.) In his observations of the visual spectra of faint stars, Rev. T. E. Espinhas discovered numerous objects which he describes as “remarkable.” (Ast. Nach. 3286.), Most of these, however, appear to be of the α Herculis type; but some are spectra in which carbon absorption is predominant (Group VI.). The most interesting observations by Mr. Espin are those of variable stars, and they tend to show that, in the stars of Group VI., the variability is accompanied by spectroscopic variations which render it difficult to distinguish them from stars of Group II., in which the carbon flutings are bright.