Problems in Astrophysics (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 edition. Excerpt: ... depths in the stellar atmospheres. Sir William and Lady Huggins advert1 to the probability of great differences in this respect between various stellar classes. In early stars they say--and none of the members of "Division b" are mature--" we may see deep down into the star, and the continuous spectrum may come 1 A tins of Spectra, p. 69. from a thick region of dense gas, throughout which little, or possibly no condensation to the liquid or the solid state takes place. Under these conditions, the absorbing gases in front of it will not be, as in the sun, of very limited thickness, but will occupy a region of vast extent." The solar H and K illustrate the character of lines generated in dense vapours at a high temperature; their "wings," as we may remind our readers, being added in the immediate vicinity of the photosphere to the comparatively definite lines produced in the upper reversing strata. Now it is a curious fact that distended lines, such as H and K, are apt to be doubly reversed. Dr. Scheiner has noticed symptoms of incipient illumination at the centres of the broad hydrogen bands distinctive of first-type stars, and they are similarly manifest in Wolf-Rayet stars showing mixed series of emission and absorption. Hence the particular significance of M. Deslandres' detection in a Aquilae of fine "chromospheric" lines of hydrogen, and occasionally of calcium and iron,1 superposed upon the dim, dusky bands indicative of the state of those substances in the reversing layer. Diffuse spectra may thus, with some probability, be assigned to abortive bright-line stars. Or they perhaps mark objects just losing the faculty of specific emission. If so, the mode of its departure is different from that...