文档介绍：CGMW5-8786
CGMW5-8687
IC 1296
CGMW5-8765
187
147
153
M 57
130
157
1941
156
141
221
M 57, drawing. 14-inch
Newtonian. Ronald Stoyan.
vation of the Ring Nebula, he wrote: “There is a rather bright star In 1861 d’Arrest reported another faint star near the central star.
in it, southeast of the center, and more very small stars. In the ring, Four years later, H. Schultz described fi ve stars inside the ring, la-
especially on the outsides of the small axis, are several small stars, ter observers up to eleven, but none of these extra stars is real. A
but there is still a lot of nebulosity which cannot be seen as indivi- reliable visual observation was made by the great Edward Emerson
dual stars.” In addition, he saw “wisps and cloudlets on the inside; Barnard in 1894 with an aperture of 40 inches, and he saw only the
the evenness of the outside is interrupted by diverging appendages, “17th panion " northwest of the central star inside
seen best around the small axis.” the nebula.”
A number of eenth-century observers reported resolution of In 1937, on deep exposures, Duncan discovered the faint outer
the nebula into faint stars. The last prominent example was Angelo halo of M 57. The “appendages” seen by Lord Rosse on the outside of
hi, who thought he saw “a ring of stars, glittering like diamond the ring actually belong to the inner, brighter part of this halo.
dust.” We may, from today’s perspective, explain some of these claims
in terms of true nebular fi ne-structure. Only William Huggins’ pionee- M 57 probably is the most popular
ring spectroscopic observations fi nally taught the visual observers Astrophysics ary nebula. The bright, cen-
that M 57 is a ring of gas. tral ring measures 86" by 62". It is surrounded by a faint inner halo of
Hence, Holden’s detailed description of M 57, as seen through a about 156" by 136" and a very faint outer halo of about ' diame-
26-inch refractor in 1875, reads: “Northern