Corona Borealis, or the Northern Crown, is the
crown Ariadne wore at her wedding. It was made by the supreme goldsmith,
Hephaestus, at his underwater smithy.
The story is connected to a more notable myth, of the Minotaur and of
Theseus, who was destined to kill it. To do so, he needed Ariadne's
help. This beautiful young maiden was the daughter of Minos, king of
Crete. She was also the half-sister to the Minotaur, the half-man half-bull
which lived at the centre of a labyrinth.
Every year Minos ordered seven young men and seven maidens from Athens to
be served up to the Minotaur. The current hero in Athens was Theseus, son of
Poseidon, and heir to the Athenian throne. Only a young man, Theseus had
already proved himself by a variety of heroic deeds. Then time came for
the yearly tribute to Crete. Theseus volunteered to be one of the
seven young men.
As he arrived in Crete, Theseus was met by Minos, who challenged the
young man to prove he was indeed the son of Poseidon. Minos threw a
gold ring into the sea, and told Theseus to fetch it.
Theseus dove into the deep, and was met by dolphins which escorted him
to the palace of the Nereids. Thetis, one of the Nereid sisters (or sea
nymphs), gave Theseus a jewelled crown that Hephaestus had made. With
the gold ring and the crown, Theseus swam back to Crete. This feat
received the loving admiration of Ariadne.
Ariadne had a magic ball of twine that could roll out by itself and follow the path to the centre of the labyrinth, where the Minotaur was kept. She promised to help Theseus kill the Minotaur if he would marry her and take her back to Athens. Theseus agreed, so she gave him the ball of twine. Theseus followed the rolling twine to the centre of the labyrinth and promptly killed the Minotaur.
Unfortunately he forgot his promise. Or, some say, he did marry
Ariadne, giving her the jewelled crown as a wedding present. And then he
later abandoned her on the isle of Naxos, on the way to Athens.
Others have it that Theseus sailed off, leaving a sleeping Ariadne to
pine for her loss. She implored her father, Zeus, to make amends. Zeus took pity and sent Dionysus to comfort his daughter.
Another version has Dionysus visiting Naxos and falling in love with
Ariadne, so he cast a spell on Theseus. Theseus then forgot all about
Ariadne and sailed off for Athens. In any case, Dionysus took her for
his bride and placed the jewelled crown of Hephaestus on her head.
They raised four sons and `lived happily ever after'. When Ariadne died Dionysus took the wedding crown and placed it in the heavens between Hercules and Bootes.
The constellation Corona Borealis is found nearly midway between
Arcturus and Vega; a little closer to the first of these stars. From
Arcturus move up to Izar (epsilon Bootis) and then east fifteen degrees
to alpha CrB.
The seven stars that make up the crown are not terribly bright, except
for Gemma, or Alphecca (alpha Coronae Borealis), which is a 2.2
magnitude star 75 light years away.
The rest of the Bayer stars vary from three to
six magnitude. The constellation includes several fine binaries, an unusual
variable, and an extremely faint cluster of galaxies.
Both alpha Coronae Borealis and beta Coronae Borealis are
spectroscopic binaries, with periods of 17.36 days and 10.5 years
Gamma CrB is also a spectroscopic binary (period uncertain) as well
as a very close visual binary (see below).
Zeta CrB is actually two stars which form a splendid binary (see
below). The two are approximately 220 light years away, given their
parallax of 0.015".
Double stars in Corona Borealis:
Gamma CrB (Struve 1967) is a close binary with an orbit of 91 years. The PA is 265º and separation about 0.2".
Eta CrB (Struve 1937) is a fine binary with orbit
of 41.5 years. Presently the companion can be found at PA 47º and separation
Zeta2 and zeta1 CrB (Struve 1965): a
pleasant pair of blue-white stars with 5.0 and 6.0 magnitudes; PA 305º,
separation 6.3". Note that zeta2 is the primary.
Sigma CrB (Struve 2032) is a slow binary,
with a period of a thousand years. Currently the companion is at PA 236º and separation 7.03"
Nu1 and nu2 CrB (Struve I 29) form a very wide (but only optical) pair of orange giants, quite suitable for binoculars: PA 164º, separation 354.7".
Variable stars in Corona Borealis:
Alpha CrB is an EA variable: 2.21 to 2.32 with period of 17.36
Beta CrB is an aCV type variable: 3.65-3.72, period 18.487 days.
Gamma CrB is a delta Sct variable: 3.80-3.86, period 0.03 days
(=43 minutes, 12 seconds).
Delta CrB: RS variable, 4.57-4.69.
SigmaA CrB is an RS and delta Sct variable with period
of 1.14 days.
R CrB is the most interesting variable here; an unusual RCB type
variable with a range from 5.71 to 14.8.
The star maintains its maximum for most of the time, perhaps several
years. Then it will start to fade, perhaps down to 8 or 9 visual
magnitude, or as faint as 14 or 15. It fluctuates for some time, not
maintaining any constant magnitude, and then years later will once again
brighten to its maximum.
Deep Sky Objects in Corona Borealis:
The only deep sky object is the Corona Borealis Galaxy Cluster.
This group is very faint but quite spectacular for those with the
The cluster is comprised of over four hundred galaxies in an area of
about one degree (the width of your thumb). The galaxies are extremely
distant, over a billion light years away, and consequently are very
faint. The brightest of the group are 16.5 visual magnitude.
To find the cluster, move two degrees west of alpha CrB and north almost a full degree. In the same field, southwest, is the sixth magnitude binary Struve 1932 (PA 57, separation 1") with a period of 203 years.
For a closer appreciation of Corona Borealis, visit the Binocular Section.