Half-hours with the Telescope - Being a Popular Guide to the Use of the Telescope as a - Means of Amusement and Instruction. by Richard Anthony Proctor
page 54 of 115 (46%)
page 54 of 115 (46%)
![]() | ![]() |
|
three nearly equal short sides alternating with the others. The star
[eta] Lyræ forms the angle next to [epsilon]. It is a wide and unequal double, as figured in Plate 3. The larger component is azure blue; the smaller is violet, and, being only of the ninth magnitude, is somewhat difficult to catch with apertures under 3 inches. The star [delta]^{2} Lyræ is orange, [delta]^{1} blue. In the same field with these are seen many other stars. The stars [gamma]^{1} and [gamma]^{2} may also be seen in a single field, the distance between them being about half the moon's mean diameter. The former is quadruple, the components being yellow, bluish, pale blue, and blue. Turn next to the stars [beta] and [gamma] Lyræ, the former a multiple, the latter an unequal double star. It is not, however, in these respects that these stars are chiefly interesting, but for their variability. The variability of [gamma] has not indeed been fully established, though it is certain that, having once been less bright, [gamma] is now considerably brighter than [beta]. The change, however, may be due to the variation of [beta] alone. This star is one of the most remarkable variables known. Its period is 12d. 21h. 53m. 10s. In this time it passes from a maximum brilliancy--that of a star of the 3·4 magnitude--to a minimum lustre equal to that of a star of the 4·3 magnitude, thence to the same maximum brilliancy as before, thence to another minimum of lustre--that of a star of the 4·5 magnitude--and so to its maximum lustre again, when the cycle of changes recommences. These remarkable changes seem to point to the existence of two unequal dark satellites, whose dimensions bear a much greater proportion to those of the bright components of [beta] Lyræ than the dimensions of the |
|