The Ring Nebula in Lyra
Publications of the Astronomical Society of the Pacific
Soon after sundown at this time of the year a bright bluish star may be seen in the northwest sky. It is the star Vega, the principal star of the constellation Lyra, and the brightest star of the northern hemisphere. The other stars of the constellation are inconspicuous. Near one of the fainter of these stars is situated the Ring Nebula in Lyra, the largest and finest of the annular nebulae. (See plate.) The nebula as it appears in the photograph is oval in shape, somewhat broader and less
... roader and less intense at the ends, and contains a star in the center. A careful examination of the original negative shows that what appears here as a plain ring devoid of fine detail is really a composite structure showing interlaced streamers of nebulosity.* As seen in a telescope of ten inches aperture, the ring is large and bright, but the central star, which is so conspicuous in this photograph, and indeed in all photographs of the nebula, is visible to the eye only with the help of two or three of the largest telescopes in the world. Mr. Barnard says that it is a very difficult object with the great telescopes of the Lick or Yerkes observatories. The ease with which this star, so difficult to see, can be photographed is due to the fact that its light is composed largely of waves from the violet region of the spectrum, which affect the photographic plate more strongly than they affect the retina of the eye. A longer exposure than that given the plate from which this reproduction is made shows the ring to be entirely filled with faint nebulosity. Professor SchaeberleI has recently made some photographs of the nebula, from a study of which he concludes that it is really a spiral nebula, and that the ringlike appearance is due simply to the fact that the wisps of nebulosity which characterize the spiral are too faint and closely wound to be observed ordinarily. If this opinion of Professor Schaeberle's is confirmed, it will be an important contribution to the subject of nebular forms and the study of the typical life-history of nebulae, as I shall show later.