“Well, now that we have
seen each other,” said the Unicorn, “if you’ll
believe in me, I’ll believe in you. Is that a bargain?”
“Yes, if you like,” said Alice.
Through the Looking-Glass
by Lewis Carroll
Monoceros, the Constellation
is unique, as is its
namesake, the Unicorn. Both are figments of the imagination; and
they are about equally hard to find. But if you will look with
sharp eyes into the winter sky and draw in your mind a triangle
with Betelgeuse, Procyon, and Sirius as the vertex stars, you
will find within that triangle a few stars of fifth magnitude.
These, and a couple of others south and east of Procyon, were
configured by Jacob Bartsch in 1624 to give this lonely part of
the heavens a name. Bartsch was a assistant to Johannes Kepler;
later, he became Kepler’s son-in-law.
As you look toward these stars you are looking diametrically opposite
to the direction of our galaxy’s center. This is the reason
for the paucity of stars. There are, though, a number of very
interesting celestial objects for study. Foremost, perhaps, is
the Rosette Nebula, although its exceptional beauty is best appreciated
with photographic exposures through large telescopes. A central
cluster of young stars is surrounded by a gas cloud of hot, ionized
hydrogen, which in turn is enclosed by a shell of cold hydrogen.
The star cluster itself (not the nebula) was discovered by the
first Astronomer Royal, John Flamsteed.
This image of the Rosette Nebula was taken by University of Michigan
Professor Patrick Seitzer with the Schmidt telescope in Chile.
[http://www.astro.lsa.umich.edu/]
Two full moons would
fit side to side within the borders of the picture. The nebula
itself has a diameter of 90 light years. Inside the nebula lies
an open cluster of bright young stars designated NGC 2244. These
stars recently formed from the nebular material. Ultraviolet light
from the hot cluster stars causes the surrounding nebula to glow.
Both cluster and nebula are visible in the Spring constellation
of Monoceros, the Unicorn. The star cluster can be glimpsed with
one's dark adapted eye under good observing conditions, and is
easily picked out with binoculars. A medium sized telescope is
needed for a good view of the nebula.
M50, a nice object for a small telescope, is an open cluster with
a red star in the field. The group lies just less than half way
from Sirius toward Procyon, midway—east to west—between
Alpha and Beta Monocerotis. It consists of from 50 to 100 stars
within an area of about 10 arcminutes diameter. On a very good
night these stars can even be seen with the unaided eye.
There are a number of interesting multiple star systems in the
constellation, including Beta Monocerotis. Another is the pretty
blue-and-gold double, Epsilon Monocerotis, which lies 10°
north of Beta.
There are a couple of variable objects in Monoceros, as well.
T Monocerotis, 2° northwest of Epsilon, is a Cepheid variable
with a period of 27 days and a magnitude range of 6.4 to 8.0.
And R Monocerotis is the variable star associated with the peculiar
Hubble’s Variable Nebula. This is a comet-shaped reflection
nebula whose brightness fluctuates without discernible rhythm,
and without a link to the visual magnitude of R-Mon. It has been
suggested that the wavering luminosity of the nebula comes from
a bipolar emission of energetic gas ejected from the star. Some
observers judge R Monocerotis to be not a star, but a protoplanetary
system, a tightly condensed nebulous region where another “solar
system” is being formed. Hubble’s Variable Nebula actually
had been discovered by William Herschel, but it was Hubble who
found, from photographs taken at several observatories, that the
nebula varied in shape and brightness. The object, listed as NGC
2261, has the further distinction of being the first object photographed
by the 200-inch Hale telescope at Mount Palomar in 1948.
Also in Monoceros is the interesting Plaskett’s Star, one
of the most massive binary systems known. Situated about 50 million
miles apart—about half the Earth-Sun distance—are two
giant stars. Their total mass is believed to be a hundred times
the mass of the Sun. In contrast, there is also a pair of red
dwarf stars in Monoceros, Ross 614. The primary has a mass just
one seventh that of the Sun; and the secondary only half of that.
Unicorns are elusive, and there are many different stories about
them, some enchanting, some just strange. In fact, unicorns have
a very definite presence in lore of all kinds, and in art, poetry
and literature. The San Francisco Museums of Fine Art have an
etching by the renowned artist Albrecht Dürer (1471-1528)
showing The Abduction of Proserpine on a Unicorn. In the
coat of arms of the United Kingdom, a unicorn is proudly shown,
together with a lion, in support of the crown. Lions and unicorns
are traditional rivals, and they are equally capable of victory
one over the other. And let it be known that a unicorn is not
simply a horse with a horn. A unicorn has cloven hooves like a
deer, a beard like a goat, and a long tail like a lion’s.
Unicorns are symbols of the mystical, the alluring and delightful;
and that is precisely because they are not literally real.