Page:Popular Science Monthly Volume 47.djvu/529

Rh appearance, and had come to bear a close resemblance to that of a planetary nebula. This has been quoted as a possible instance of a celestial collision through whose effects the solid colliding masses were vaporized and expanded into a nebula. At present the star is very faint and can only be seen with the most powerful telescopes.

Underneath Cygnus we notice the small constellation Vulpecula. It contains a few objects worthy of attention, the first being the nebula 4532, the "dumb-bell nebula" of Lord Rosse. With the four-inch, and better with the five-inch, we are able to perceive that it consists of two close-lying tufts of misty light. Many stars surround it, and large telescopes show them scattered between the two main masses of the nebula. The star 11 points out the place where a new star of the third magnitude appeared in 1670. Σ 2695 is a close double, magnitudes six and eight, distance 1·4″, p. 82°.

We turn to map No. 18, and, beginning at the western end of the constellation Aquarius, we find the variable T, which ranges between magnitudes seven and thirteen in a period of about two hundred and three days. Its near neighbor Σ 2729 is a very close double, beyond the separating power of our five-inch, the magnitudes being six and seven, distance 0·6″, p. 176°. Σ 2745, also known as 12 Aquarii, is a good double for the three-inch. Its magnitudes are six and eight, distance 2·8″, p. 190°. In ζ we discover a beauty. It is a slow binary of magnitudes four and five, distance 3·3″ p. 325°. According to some observers both stars have a greenish tinge. The star 41 is a wider double, magnitudes six and eight, distance 5″, p. 115°, colors yellow and blue. The uncommon stellar contrast of white with light garnet is exhibited by τ, magnitudes six and nine, distance 27″, p. 115°. Yellow and blue occur again conspicuously in ψ, magnitudes four and a half and eight and a half, distance 50″, p. 310°. Rose and emerald have been recorded as the colors exhibited in Σ 2998, whose magnitudes are five and seven, distance 13·5″, p. 346°.

The variables S and R are both red. The former ranges between magnitudes eight and twelve, period two hundred and eighty days, and the latter between magnitudes six and eleven, period about three hundred and ninety days.

The nebula 4628 is Rosse's "Saturn nebula," so called because with his great telescope it presented the appearance of a nebulous model of the planet Saturn. With our five-inch we see it simply as a planetary nebula. We may also glance at another nebula, 4678, which appears circular and is pinned with a little star at the edge.

The small constellation Equuleus contains a surprisingly large number of interesting objects. Σ 2735 is a rather close double,