Cepheus, King of Joppa
and his queen Cassiopeia are well known in the mythology of Greece.
The story has been told many times of their daughter Andromeda
and her rescue from the sea monster Cetus by the hero Perseus.
Of these characters in the northern sky, the king is perhaps least
known, for his constellation has no particularly bright stars
and no particularly obvious pattern. Yet because he was a descendent
of Jupiter and Io, he was held in high regard and continues to
rule from his position in the northern sky.
About thirty centuries ago there was in China a famous charioteer
named Tsao Fu. He was a driver of great skill, and was placed
in charge of the eight magnificent horses of the emperor Mu Wang.
As the emperor grew older he became determined to visit the slopes
of Mount K’uen Lun, where lay the Western Paradise in the
very center of the world. Amidst its wondrous gardens stood trees
that bore fruit of pearls and jade. There was also a magic peach
tree, it was said, that flowered only once in three thousand years.
This was the garden of the queen of the fairies, Hsi Wang Mu;
and each time the peaches were ripe, she would invite all the
gods, and perhaps a mortal specially favored, to join her in a
feast of the peaches. Such a mortal who tasted the peaches would
live with the gods for the next three thousand years.
Mu Wang summoned his chariot and his horses, and with Tsao Fu
in command set off on this dangerous adventure over many swift
rivers and across difficult mountain passes to reach the land
of immortality.
Neither the emperor nor Tsao Fu was ever seen or heard from again.
It can only be concluded that they indeed reached their goal,
and that Mu Wang is still living with the gods on the slopes of
the magic mountain. The charioteer was rewarded for his dedicated
efforts by being transported up into the sky, where he looks down
forever from the stars that we know as Cepheus.
Ced 214 (H II Region in Cepheus, often erroneously referred
to as NG 7822)
This fine field in Cepheus was photographed by Axel Mellinger
in August 1996 from the Barcroft Research Station in the White
Mountains. He used a Newtonian 800-mm f/4 telescope with Kodak
Pro 400 PPF film and a 35-minute exposure.
The brightest of all the
stars in the constellation is Alderamin, or Alpha Cephei, at magnitude
2.6. Its importance is still to come, however, as in just seventy-three
thousand years it will assume the status of the Pole Star.
Of more importance is Delta Cephei, whose story is certainly a
tribute to the potential of true scientists who may be handicapped.
For in 1784 John Goodricke, an eighteen-year-old student in England,
deaf since birth, discovered that this star was of variable brightness.
His measurements led him to the conclusion that the star’s
periodic rise and fall in luminosity was unlike that of such stars
as Algol, whose fluctuations are attributable to eclipses by binary
partners. In reporting his findings to the Royal Society, Goodricke
suggested that Delta Cephei was an “intrinsic” variable,
undergoing true change in its light output. Such stars, now known
as Cepheid variables, show spectral changes that coincide with
the brightness periodicity. It followed that the absolute magnitude
of Cepheids are related to their period, and from this idea the
distance of these stars can be ascertained by measuring their
observed magnitudes. This is the work that led Edwin Hubble in
1924 to use the Cepheid variables in the Andromeda “nebula”
to identify it as a true star system—a galaxy apart from
our own.
Another interesting star is Mu Cephei, a star so deep red in color
that it was named the “Garnet Star” by Sir William Herschel.
It is a pulsating red giant, similar to Betelgeuse in Orion. Several
hundred times the diameter of the Sun, the Garnet Star shines
with a luminosity perhaps twelve thousand times that of the Sun.
Watch this star with the naked eye over a period of several months
to observe its variability.
Although there are no Messier objects in Cepheus, there are quite
a number of interesting deep-sky targets for small telescopes,
as well as a few double stars of note. One of these is known as
Krüger 60. This pair is only about 13 light years away from
us, and each of the stars is a red dwarf. The smaller of these
is one of the smallest stars known, with a mass only a seventh
that of the Sun. This midget has an irregular history of sudden
flares which may double the star’s luminosity in a period
of one or two minutes.