IN SUMMER STAR-LANDS
"I heard the trailing garments of the night
Sweep through her marble halls,
I saw her sable skirts all fringed with light
From the celestial walls."--H. W. LONGFELLOW.
In the soft air of a summer night, when fireflies are flashing their
lanterns over the fields, the stars do not sparkle and blaze like those
that pierce the frosty skies of winter. The light of Sirius, Aldebaran,
Rigel, and other midwinter brilliants possesses a certain gemlike
hardness and cutting quality, but Antares and Vega, the great summer
stars, and Arcturus, when he hangs westering in a July night, exhibit a
milder radiance, harmonizing with the character of the season. This
difference is, of course, atmospheric in origin, although it may be
partly subjective, depending upon the mental influences of the mutations
of Nature.
[Illustration: MAP NO. 12.]
The constellation Scorpio is nearly as striking in outline as Orion, and
its brightest star, the red Antares (alpha in map No. 12), carries
concealed in its rays a green jewel which, to the eye of the enthusiast
in telescopic recreation, appears more beautiful and inviting each time
that he penetrates to its hiding place.
We shall begin our night's work with this object, and the four-inch
glass will serve our purpose, although the untrained observer would be
more certain of success with the five-inch. A friend of mine has seen
the companion of Antares with a three-inch, but I have never tried the
star with so small an aperture. When the air is steady and the companion
can be well viewed, there is no finer sight among the double stars. The
contrast of colors is beautifully distinct--fire-red and bright green.
The little green star has been seen emerging from behind the moon, ahead
of its ruddy companion. The magnitudes are one and seven and a half or
eight, distance 3", p. 270 deg.. Antares is probably a binary, although its
binary character has not yet been established.
A slight turn of the telescope tube brings us to the star sigma, a wide
double, the smaller component of which is blue or plum-colored;
magnitudes four and nine, distance 20", p. 272 deg.. From sigma we pass to
beta, a very beautiful object, of which the three-inch gives us a
splendid view. Its two components are of magnitudes two and six,
distance 13", p. 30 deg.; colors, white and bluish. It is interesting to
know that the larger star is itself double, although none of the
telescopes we are using can split it. Burnham discovered that it has a
tenth-magnitude companion; distance less than 1", p. 87 deg..
And now for a triple, which will probably require the use of our largest
glass. Up near the end of the northern prolongation of the constellation
we perceive the star xi. The three-inch shows us that it is double; the
five-inch divides the larger star again. The magnitudes are respectively
five, five and a half, and seven and a half, distances 0.94", p. 215 deg.,
and 7", p. 70 deg..
A still more remarkable star, although one of its components is beyond
our reach, is nu. With the slightest magnifying this object splits up
into two stars, of magnitudes four and seven, situated rather more than
40" apart. A high power divides the seventh-magnitude companion into
two, each of magnitude six and a half, distance 1.8", p. 42 deg.. But (and
this was another of Burnham's discoveries) the fourth-magnitude star
itself is double, distance 0.8", p. about 0 deg.. The companion in this case
is of magnitude five and a half.
Next we shall need a rather low-power eyepiece and our largest aperture
in order to examine a star cluster, No. 4173, which was especially
admired by Sir William Herschel, who discovered that it was not, as
Messier had supposed, a circular nebula. Herschel regarded it as the
richest mass of stars in the firmament, but with a small telescope it
appears merely as a filmy speck that has sometimes been mistaken for a
comet. In 1860 a new star, between the sixth and seventh magnitude in
brilliance, suddenly appeared directly in or upon the cluster, and the
feeble radiance of the latter was almost extinguished by the superior
light of the stranger. The latter disappeared in less than a month, and
has not been seen again, although it is suspected to be a variable, and,
as such, has been designated with the letter T. Two other known
variables, both very faint, exist in the immediate neighborhood.
According to the opinion that was formerly looked upon with favor, the
variable T, if it is a variable, simply lies in the line of sight
between the earth and the star cluster, and has no actual connection
with the latter. But this opinion may not, after all, be correct, for
Mr. Bailey's observations show that variable stars sometimes exist in
large numbers in clusters, although the variables thus observed are of
short period. The cluster 4183, just west of Antares, is also worth a
glance with the five-inch glass. It is dense, but its stars are very
small, so that to enjoy its beauty we should have to employ a large
telescope. Yet there is a certain attraction in these far-away glimpses
of starry swarms, for they give us some perception of the awful
profundity of space. When the mind is rightly attuned for these
revelations of the telescope, there are no words that can express its
impressions of the overwhelming perspective of the universe.
The southern part of the constellation Ophiuchus is almost inextricably
mingled with Scorpio. We shall, therefore, look next at its attractions,
beginning with the remarkable array of star clusters 4264, 4268, 4269,
and 4270. All of these are small, 2' or 3' in diameter, and globular in
shape. No. 4264 is the largest, and we can see some of the stars
composing it. But these clusters, like those just described in Scorpio,
are more interesting for what they signify than for what they show; and
the interest is not diminished by the fact that their meaning is more or
less of a mystery. Whether they are composed of pygmy suns or of great
solar globes like that one which makes daylight for the earth, their
association in spherical groups is equally suggestive.
There are two other star clusters in Ophiuchus, and within the limits of
map No. 12, both of which are more extensive than those we have just
been looking at. No. 4211 is 5' or 6' in diameter, also globular,
brighter at the center, and surrounded by several comparatively
conspicuous stars. No. 4346 is still larger, about half as broad as the
moon, and many of its scattered stars are of not less than the ninth
magnitude. With a low magnifying power the field of view surrounding the
cluster appears powdered with stars.
There are only two noteworthy doubles in that part of Ophiuchus with
which we are at present concerned: 36, whose magnitudes are five and
seven, distance 4.3", p. 195 deg., colors yellow and red; and 39, magnitudes
six and seven and a half, distance 12", p. 356 deg., colors yellow or
orange and blue. The first named is a binary whose period has not been
definitely ascertained.
The variable R has a period a little less than three hundred and three
days. At its brightest it is of magnitude seven or eight, and at minimum
it diminishes to about the twelfth magnitude.
The spot where the new star of 1604 appeared is indicated on the map.
This was, with the exception of Tycho's star in 1572, the brightest
temporary star of which we possess a trustworthy account. It is
frequently referred to as Kepler's star, because Kepler watched it with
considerable attention, but unfortunately he was not as good an observer
as Tycho was. The star was first seen on October 10, 1604, and was then
brighter than Jupiter. It did not, however, equal Venus. It gradually
faded and in March, 1606, disappeared. About twelve degrees northwest of
the place of the star of 1604, and in that part of the constellation
Serpens which is included in map No. 12, we find the location of another
temporary star, that of 1848. It was first noticed by Mr. Hind on April
28th of that year, when its magnitude was not much above the seventh,
and its color was red. It brightened rapidly, until on May 2d it was of
magnitude three and a half. Then it began to fade, but very slowly, and
it has never entirely disappeared. It is now of the twelfth or
thirteenth magnitude.
In passing we may glance with a low power at nu Serpentis, a wide
double, magnitudes four and nine, distance 50", p. 31 deg., colors
contrasted but uncertain.
Sagittarius and its neighbor, the small but rich constellation Scutum
Sobieskii, attract us next. We shall first deal with the western
portions of these constellations which are represented on Map No. 12.
The star in Sagittarius is a wide triple, magnitudes three and a half,
nine and a half, and ten, distances 40", p. 315 deg., and 45", p. 114 deg.. But
the chief glory of Sagittarius (and the same statement applies to Scutum
Sobieskii) lies in its assemblage of star clusters. One of these, No.
4361, also known as M 8, is plainly visible to the naked eye as a bright
spot in the Milky Way. We turn our five-inch telescope, armed with a low
magnifying power, upon this subject and enjoy a rare spectacle. As we
allow it to drift through the field we see a group of three
comparatively brilliant stars advancing at the front of a wonderful
train of mingled star clusters and nebulous clouds. A little northwest
of it appears the celebrated trifid nebula, No. 4355 on the map. There
is some evidence that changes have occurred in this nebula since its
discovery in the last century. Barnard has made a beautiful photograph
showing M 8 and the trifid nebula on the same plate, and he remarks that
the former is a far more remarkable object than its more famous
neighbor. Near the eastern border of the principal nebulous cloud there
is a small and very black hole with a star poised on its eastern edge.
This hole and the star are clearly shown in the photograph.
Cluster No. 4397 (M 24) is usually described as resembling, to the naked
eye, a protuberance on the edge of the Milky Way. It is nearly three
times as broad as the moon, and is very rich in minute stars, which are
at just such a degree of visibility that crowds of them continually
appear and disappear while the eye wanders over the field, just as faces
are seen and lost in a vast assemblage of people. This kind of luminous
agitation is not peculiar to M 24, although that cluster exhibits it
better than most others do on account of both the multitude and the
minuteness of its stars.
A slight sweep eastward brings us to yet another meeting place of stars,
the cluster M 25, situated between the variables U and V. This is
brilliant and easily resolved into its components, which include a
number of double stars.
The two neighboring variables just referred to are interesting. U has a
period of about six days and three quarters, and its range of magnitude
runs from the seventh down to below the eighth. V is a somewhat
mysterious star. Chandler removed it from his catalogue of variables
because no change had been observed in its light by either himself,
Sawyer, or Yendell. Quirling, the discoverer of its variability, gave
the range as between magnitudes 7.6 and 8.8. It must, therefore, be
exceedingly erratic in its changes, resembling rather the temporary
stars than the true variables.
In that part of Scutum Sobieskii contained in map No. 12 we find an
interesting double, Sigma 2325, whose magnitudes are six and nine,
distance 12.3", p. 260 deg., colors white and orange. Sigma 2306 is a
triple, magnitudes seven, eight, and nine, distances 12", p. 220 deg., and
0.8", p. 68 deg.. The third star is, however, beyond our reach. The colors
of the two larger are respectively yellow and violet.
The star cluster 4400 is about one quarter as broad as the moon, and
easily seen with our smallest aperture.
[Illustration: MAP NO. 13.]
Passing near to the region covered by map No. 13, we find the remaining
portions of the constellations Sagittarius and Scutum Sobieskii. It will
be advisable to finish with the latter first. Glance at the clusters
4426 and 4437. Neither is large, but both are rich in stars. The nebula
4441 is a fine object of its kind. It brightens toward the center, and
Herschel thought he had resolved it into stars. The variable R is
remarkable for its eccentricities. Sometimes it attains nearly the
fourth magnitude, although usually at maximum it is below the fifth,
while at minimum it is occasionally of the sixth and at other times of
the seventh or eighth magnitude. Its period is irregular.
Turning back to Sagittarius, we resume our search for interesting
objects there, and the first that we discover is another star cluster,
for the stars are wonderfully gregarious in this quarter of the heavens.
The number our cluster bears on the map is 4424, corresponding with M 22
in Messier's catalogue. It is very bright, containing many stars of the
tenth and eleventh magnitudes, as well as a swarm of smaller ones. Sir
John Herschel regarded the larger stars in this cluster as possessing a
reddish tint. Possibly there was some peculiarity in his eye that gave
him this impression, for he has described a cluster in the constellation
Toucan in the southern hemisphere as containing a globular mass of
rose-colored stars inclosed in a spherical shell of white stars. Later
observers have confirmed his description of the shape and richness of
this cluster in Toucan, but have been unable to perceive the red hue of
the interior stars.
The eastern expanse of Sagittarius is a poor region compared with the
western end of the constellation, where the wide stream of the Milky Way
like a great river enriches its surroundings. The variables T and R are
of little interest to us, for they never become bright enough to be seen
without the aid of a telescope. In 54 we find, however, an interesting
double, which with larger telescopes than any of ours appears as a
triple. The two stars that we see are of magnitudes six and seven and a
half, distance 45", p. 42 deg., colors yellow and blue. The third star,
perhaps of thirteenth magnitude, is distant 36", p. 245 deg..
Retaining map No. 13 as our guide, we examine the western part of the
constellation Capricornus. Its leader alpha is a naked-eye double, the
two stars being a little more than 6' apart. Their magnitudes are three
and four, and both have a yellowish hue. The western star is alpha^1,
and is the fainter of the two. The other is designated as alpha^2. Both
are double. The components of alpha^1 are of magnitudes four and eight
and a half, distance 44", p. 220 deg.. With the Washington twenty-six-inch
telescope a third star of magnitude fourteen has been found at a
distance of 40", p. 182 deg.. In alpha^2 the magnitudes of the components
are three and ten and a half, distance 7.4", p. 150 deg.. The smaller star
has a companion of the twelfth or thirteenth magnitude, distance 1.2",
p. 240 deg.. This, of course, is hopelessly beyond our reach. Yet another
star of magnitude nine, distance 154", p. 156, we may see easily.
Dropping down to beta, we find it to be a most beautiful and easy
double, possessing finely contrasted colors, gold and blue. The larger
star is of magnitude three, and the smaller, the blue one, of magnitude
six, distance 205", p. 267 deg.. 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 deg..
Still farther south and nearly in a line drawn from alpha through beta
we find a remarkable group of double stars, sigma, pi, rho, and omicron.
The last three form a beautiful little triangle. We begin with sigma,
the faintest of the four. The magnitudes of its components are six and
nine, distance 54", p. 177 deg.. In pi the magnitudes are five and nine,
distance 3.4", p. 145 deg.; in rho, magnitudes five and eight, distance
3.8", p. 177 deg. (a third star of magnitude seven and a half is seen at a
distance of 4', p. 150 deg.); in omicron, magnitudes six and seven, distance
22", p. 240 deg..
The star cluster 4608 is small, yet, on a moonless night, worth a glance
with the five-inch.
[Illustration: MAP NO. 14.]
We now pass northward to the region covered by map No. 14, including the
remainder of Ophiuchus and Serpens. Beginning with the head of Serpens,
in the upper right-hand corner of the map, we find that beta, of
magnitude three and a half, has a ninth-magnitude companion, distance
30", p. 265 deg.. The larger star is light blue and the smaller one
yellowish. The little star nu is double, magnitudes five and nine,
distance 50", p. 31 deg., colors contrasted but uncertain. In delta we find
a closer double, magnitudes three and four, distance 3.5", p. 190 deg.. It
is a beautiful object for the three-inch. The leader of the
constellation, alpha, of magnitude two and a half, has a faint companion
of only the twelfth magnitude, distance 60", p. 350 deg.. 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 turn again into Ophiuchus, and find immediately the
very interesting double, lambda, whose components are of magnitudes four
and six, distance 1", p. 55 deg.. 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. Sigma 2166 consists of two stars of magnitudes
six and seven and a half, distance 27", p. 280 deg.. Sigma 2173 is a double
of quite a different order. The magnitudes of its components are both
six, the distance in 1899 0.98", p. 331 deg.. 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 tau is a fine triple,
magnitudes five, six, and nine, distances 1.8", p. 254 deg., and 100", p.
127 deg.. 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 and eight, distance 55", p. 144 deg., colors
finely contrasted, pale yellow and red.
Much more interesting, however, is 70, a binary whose components have
completed a revolution since their discovery by Sir William Herschel,
the period being ninety-five years. The magnitudes are four and six, or,
according to Hall, five and six, distance in 1894 2.3"; in 1900, 1.45",
according to Maw. Hall says the apparent distance when the stars are
closest is about 1.7", and when they are widest 6.7". This star is one
of those whose parallax has been calculated with a reasonable degree of
accuracy. Its distance from us is about 1,260,000 times the distance of
the sun, the average distance apart of the two stars is about
2,800,000,000 miles (equal to the distance of Neptune from the sun), and
their combined mass is three times that of the sun. Hall has seen in the
system of 70 Ophiuchi three stars of the thirteenth magnitude or less,
at distances of about 60", 90", and 165" respectively.
The star 73 is also a close double, and beyond our reach. Its magnitudes
are six and seven, distance 0.7", p. 245 deg.. It is, no doubt, a binary.
Three star clusters in Ophiuchus remain to be examined. The first of
these, No. 4256, is partially resolved into stars by the five-inch. No.
4315 is globular, and has a striking environment of bystanding stars. It
is about one quarter as broad as the full moon, and our largest aperture
reveals the faint coruscation of its crowded components. No. 4410 is a
coarser and more scattered star swarm--a fine sight!
Farther toward the east we encounter a part of Serpens again, which
contains just one object worth glancing at, the double theta, whose
stars are of magnitudes four and four and a half, distance 21", p. 104 deg..
Color, both yellow, the smaller star having the deeper hue.
[Illustration: MAP NO. 15.]
Let us next, with the guidance of map No. 15, enter the rich star fields
of Hercules, and of the head and first coils of Draco. According to
Argelander, Hercules contains more stars visible to the naked eye than
any other constellation, and he makes the number of them one hundred and
fifty-five, nearly two thirds of which are only of the sixth magnitude.
But Heis, who saw more naked-eye stars than Argelander, makes Ursa Major
precisely equal to Hercules in the number of stars, his enumeration
showing two hundred and twenty-seven in each constellation, while,
according to him, Draco follows very closely after, with two hundred and
twenty stars. Yet, on account of the minuteness of the majority of their
stars, neither of these constellations makes by any means as brilliant a
display as does Orion, to which Argelander assigns only one hundred and
fifteen naked-eye stars, and Heis one hundred and thirty-six.
We begin in Hercules with the star kappa, a pretty little double of
magnitudes five and a half and seven, distance 31", p. 10 deg., colors
yellow and red. Not far away we find, in gamma, a larger star with a
fainter companion, the magnitudes in this case being three and a half
and nine, distance 38", p. 242 deg., colors white and faint blue or lilac.
One of the most beautiful of double stars is alpha Herculis. The
magnitudes are three and six, distance 4.7", p. 118 deg., colors orange and
green, very distinct. Variability has been ascribed to each of the stars
in turn. It is not known that they constitute a binary system, because
no certain evidence of motion has been obtained. Another very beautiful
and easily separated double is delta, magnitudes three and eight,
distance 19", p. 175 deg., colors pale green and purple.
Sweeping northwestward to zeta, we encounter a celebrated binary, to
separate which at present requires the higher powers of a six-inch
glass. The magnitudes are three and six and a half, distance in 1899,
0.6", p. 264 deg.; in 1900, 0.8", p. 239 deg.. The period of revolution is
thirty-five years, and two complete revolutions have been observed. The
apparent distance changes from 0.6" to 1.6". They were at their extreme
distance in 1884.
Two pleasing little doubles are Sigma 2101, magnitudes six and nine,
distance 4", p. 57 deg., and Sigma 2104, magnitudes six and eight, distance
6", p. 20 deg.. At the northern end of the constellation is 42, a double
that requires the light-grasping power of our largest glass. Its
magnitudes are six and twelve, distance 20", p. 94 deg.. In rho we discover
another distinctly colored double, both stars being greenish or bluish,
with a difference of tone. The magnitudes are four and five and a half,
distance 3.7", p. 309 deg.. But the double 95 is yet more remarkable for the
colors of its stars. Their magnitudes are five and five and a half,
distance 6", p. 262 deg., colors, according to Webb, "light apple-green and
cherry-red." But other observers have noted different hues, one calling
them both golden yellow. I think Webb's description is more nearly
correct. Sigma 2215 is a very close double, requiring larger telescopes
than those we are working with. Its magnitudes are six and a half and
eight, distance 0.7", p. 300 deg.. It is probably a binary. Sigma 2289 is
also close, but our five-inch will separate it: magnitudes six and
seven, distance 1.2", p. 230 deg..
Turning to , we have to deal with a triple, one of whose stars is at
present beyond the reach of our instruments. The magnitudes of the two
that we see are four and ten, distance 31", p. 243 deg.. The tenth-magnitude
star is a binary of short period (probably less than fifty years), the
distance of whose components was 2" in 1859, 1" in 1880, 0.34" in 1889,
and 0.54" in 1891, when the position angle was 25 deg., and rapidly
increasing. The distance is still much less than 1".
For a glance at a planetary nebula we may turn with the five-inch to No.
4234. It is very small and faint, only 8" in diameter, and equal in
brightness to an eighth-magnitude star. Only close gazing shows that it
is not sharply defined like a star, and that it possesses a bluish tint.
Its spectrum is gaseous.
The chief attraction of Hercules we have left for the last, the famous
star cluster between eta and zeta, No. 4230, more commonly known as M
13. On a still evening in the early summer, when the moon is absent and
the quiet that the earth enjoys seems an influence descending from the
brooding stars, the spectacle of this sun cluster in Hercules, viewed
with a telescope of not less than five-inches aperture, captivates the
mind of the most uncontemplative observer. With the Lick telescope I
have watched it resolve into separate stars to its very center--a scene
of marvelous beauty and impressiveness. But smaller instruments reveal
only the in-running star streams and the sprinkling of stellar points
over the main aggregation, which cause it to sparkle like a cloud of
diamond dust transfused with sunbeams. The appearance of flocking
together that those uncountable thousands of stars present calls up at
once a picture of our lone sun separated from its nearest stellar
neighbor by a distance probably a hundred times as great as the entire
diameter of the spherical space within which that multitude is
congregated. It is true that unless we assume what would seem an
unreasonable remoteness for the Hercules cluster, its component stars
must be much smaller bodies than the sun; yet even that fact does not
diminish the wonder of their swarming. Here the imagination must bear
science on its wings, else science can make no progress whatever. It is
an easy step from Hercules to Draco. In the conspicuous diamond-shaped
figure that serves as a guide-board to the head of the latter, the
southernmost star belongs not to Draco but to Hercules. The brightest
star in this figure is gamma, of magnitude two and a half, with an
eleventh-magnitude companion, distant 125", p. 116 deg.. Two stars of
magnitude five compose nu, their distance apart being 62", p. 312 deg.. A
more interesting double is , magnitudes five and five, distance 2.4", p.
158 deg.. Both stars are white, and they present a pretty appearance when
the air is steady. They form a binary system of unknown period. Sigma
2078 (also called 17 Draconis) is a triple, magnitudes six, six and a
half, and six, distances 3.8", p. 116 deg., and 90", p. 195 deg.. Sigma 1984 is
an easy double, magnitudes six and a half and eight and a half, distance
6.4", p. 276 deg.. The star eta is a very difficult double for even our
largest aperture, on account of the faintness of one of its components.
The magnitudes are two and a half and ten, distance 4.7", p. 140 deg.. Its
near neighbor, Sigma 2054, may be a binary. Its magnitudes are six and
seven, distance 1", p. 0 deg.. In Sigma 2323 we have another triple,
magnitudes five, eight and a half, and seven, distances 3.6", p. 360 deg.,
and 90", p. 22 deg., colors white, blue, and reddish. A fine double is
epsilon, magnitudes five and eight, distance 3", p. 5 deg..
The nebula No. 4373 is of a planetary character, and interesting as
occupying the pole of the ecliptic. A few years ago Dr. Holden, with the
Lick telescope, discovered that it is unique in its form. It consists of
a double spiral, drawn out nearly in the line of sight, like the thread
of a screw whose axis lies approximately endwise with respect to the
observer. There is a central star, and another fainter star is involved
in the outer spiral. The form of this object suggests strange ideas as
to its origin. But the details mentioned are far beyond the reach of
our instruments. We shall only see it as a hazy speck. No. 4415 is
another nebula worth glancing at. It is Tuttle's so-called variable
nebula.
[Illustration: MAP NO. 16.]
There are three constellations represented on map No. 16 to which we
shall pay brief visits. First Aquila demands attention. Its doubles may
be summarized as follows: 11, magnitudes five and nine, distance 17.4",
p. 252 deg.; pi, magnitudes six and seven, distance 1.6", p. 122 deg.; 23,
magnitudes six and ten, distance 3.4", p. 12 deg.--requires the five-inch
and good seeing; 57, magnitudes five and six, distance 36", p. 170 deg.;
Sigma 2654, magnitudes six and eight, distance 12", p. 234 deg.; Sigma 2644,
magnitudes six and seven, distance 3.6", p. 208 deg..
The star eta is an interesting variable between magnitudes three and a
half and 4.7; period, seven days, four hours, fourteen minutes. The
small red variable R changes from magnitude six to magnitude seven and a
half and back again in a period of three hundred and fifty-one days.
Star cluster No. 4440 is a striking object, its stars ranging from the
ninth down to the twelfth magnitude.
Just north of Aquila is the little constellation Sagitta, containing
several interesting doubles and many fine star fields, which may be
discovered by sweeping over it with a low-power eyepiece. The star zeta
is double, magnitudes five and nine, distance 8.6", p. 312 deg.. The larger
star is itself double, but far too close to be split, except with very
large telescopes. In theta we find three components of magnitudes seven,
nine, and eight respectively, distances 11.4", p. 327 deg., and 70", p.
227 deg.. A wide double is epsilon, magnitudes six and eight, distance 92",
p. 81 deg.. Nebula No. 4572 is planetary.
Turning to Delphinus, we find a very beautiful double in gamma,
magnitudes four and five, distance 11", p. 273 deg., colors golden and
emerald. The leader alpha, which is not as bright as its neighbor beta,
and which is believed to be irregularly variable, is of magnitude four,
and has a companion of nine and a half magnitude at the distance 35", p.
278 deg.. At a similar distance, 35", p. 335 deg., beta has an
eleventh-magnitude companion, and the main star is also double, but
excessively close, and much beyond our reach. It is believed to be a
swiftly moving binary, whose stars are never separated widely enough to
be distinguished with common telescopes.