Page:Popular Science Monthly Volume 47.djvu/211

Rh blue one, of magnitude six; distance 205″, p. 267°. Between them there is a very faint star which larger telescopes than ours divide into two, each of magnitude eleven and a half; separated 3″, P. 325°.

Still farther south and nearly in a line drawn from α through β, we find a remarkable group of double stars, σ, π, ρ, and ο. The last three form a beautiful little triangle. We begin with σ, the faintest of the four. The magnitudes of its components are six and nine; distance 54″, p. 177°. In π, the magnitudes are five and nine, distance 3·4″, p. 145°; in ρ, magnitudes five and eight, distance 3·8″, p. 177° (a third star of magnitude seven and a half is seen at a distance of 4', p. 150°); in ο, magnitudes six and seven, distance 22″, p. 240°.

The star cluster 4608 is small, yet, on a moonless night, worth a glance with the five-inch.

We now pass northward to the region covered by map No. 14, indludingincluding [sic] the remainder of Ophiuchus and Serpens. Beginning with the head of Serpens, in the upper right-hand corner of the map, we find that β, of magnitude three and a half, has a ninth-magnitude companion, distance 30″, p. 265°. The larger star is light blue and the smaller one yellowish. The little star ν, is double, magnitudes five and nine, distance 50″, p. 31°, colors contrasted but uncertain. In δ we find a closer double, magnitudes three and four, distance 3·5″, p. 190°. It is a beautiful object for the three-inch. The leader of the constellation, α, of magnitude two and a half, has a faint companion of only the twelfth magnitude, distance 60″, p. 350°. The small star is bluish. The variable R has a period about a week short of one year, and at maximum exceeds the sixth magnitude, although sinking at minimum to less than the eleventh. Its color is ruddy.

Passing eastward, we come again into Ophiuchus, and find immediately the very interesting double, λ, whose components are of magnitudes four and six, distance 1·2″, p. 45°. This is a long-period binary, and, notwithstanding the closeness of its stars, our four-inch should separate them when the seeing is fine. We shall do better, however, to try with the five-inch. Σ 2166 consists of two stars of magnitudes six and seven and a half, distance 27″, p. 280°. Σ 2173 is a double of quite a different order. The magnitudes of its components are both six, the distance in 1894 1·14″, p. 357°. It is evidently a binary in rapid motion, as the distance changed from about a quarter of a second in 1881 to more than a second in 1894. The star τ, is a fine triple, magnitudes five, six, and nine, distances 1·8″, p. 254°, and 100″, p. 127°. The close pair is a binary system with a long period of revolution, estimated at about two hundred years. We discover another group of remarkable doubles in 67, 70, and 73. In the first-named star the magnitudes are four