Delphinus the Dolphin is a small constellation that can be seen in the summer months close to the star Altair one of the summer triangle stars.
There are many stories attached to the constellation, one of the most popular is from Greece where
it is said that a dolphin rescued the musician Arion who was travelling from
Tarentum to Corinth and while playing music charmed some dolphins. When the
crew of the ship he was travelling on robbed him and threw him overboard the
dolphins rescued him and carried Arion on their backs the shore and safety. And
for that good deed a dolphin was placed in the sky forever.
It is one of the smaller of the classical constellations and
as always there are lots of stories concerning it. There is some suggestion
that Hipparchus wanted to place the stars in the constellation Delphinus into
the constellation of Equuleus or Foal. However, this dd not happen and it
stayed as a separate star group, it was always regarded as the most remarkable
of the marine creatures.
The stars alpha, beta, gamma and zeta Delphinus are often
described as representing Job’s Coffin. No one seem to know why or when this
term was first used.
The Roman poet Ovid said it was clarum sidus or the famous
star of the girls and it was personified as Amphitrite the goddess of the sea, because
the dolphin induced Amphitrite to become the wife of Neptune.
The Hindu astronomers knew it as shi-shu-mara or a porpoise
which was also ascribed to Draco.
The Arab astronomer Al Biruni gave it the title Al Ka fidor
the Riding Camel, while other Arabian astronomers referred to it as Dulfirm a
marine animal friendly to man.
Delphinus forms a shape like a small version of the Plough. The two brightest stars are beta and alpha in that order; beta is an F class star and has a magnitude of 3.6 its 97 light years away and has a surface temperature of about 6,500 degrees making it warmer than our Sun. Alpha on the other hand is a B class star with a magnitude of 3.8 and with a surface temperature of around 11,500 degrees and is 241 light years away.
Neither star appears to have a classical name but in 1814 in
the Palermo star catalogue the names
Sualocin were given to alpha while beta became Rotanev. It caused a real
mystery it was a puzzle that Admiral Smythe was unable to solve. This is
strange because he knew the staff at the Palermo Observatory very well. It
would be TW Webb who solved the puzzle, he realised that be reversing the letters and reading Nicolaus Venator, the
Latinised form of Niccolo Cacciatore, this was the name of the assistant and
successor of Piazzi at Palermo.
Epsilon which at magnitude 4.0 has surprisingly got an
Arabic name, it was known as Al Dhanab al Dulfim or the Dolphin’s Tail. Its 330
light years away and is a B class giant star with a very hot temperature of
13,000 degree. While in China the star was known as Pae Chaou or the Rotten
Melon.
Gamma which has no name is a F class star 115 light years
away, with a magnitude of 4.3 and a temperature of around 6,000 degrees similar
to the Sun which has a surface temperature of 5,800 degrees
Delta also has no name is a magnitude 4.3 star an A class
star hotter than the Sun and is 223 light yeas distant.
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