The constellation of Argo Navis no longer exists as one constellation. It was at one time the largest constellation in the sky but in the 1750s the French astronomer Nicolas -Louis de Lacaille 1713-1762 divided it up into three smaller constellations, Carina the Keel Puppis the Poop and Vela the Sails.
The original
constellation was built by Glaucus for Jason and his 50 argonauts on their
quest for the Golden Fleece. This fleece had come from a magical ram which was
able to fly and which has rescued two royal children from a cruel stepmother,
carrying them to the land of king Aetes. After the ram died the fleece was
placed in a tree in a scared grove guarded by a particularly nasty dragon. Much
to the annoyance of King Aetes Jason managed to kill the dragon and took the
fleece back to his own country.
Among the heroes concerned in this expedition were Hercules
and the heavenly twins Castor and Pollux. We will meet them in the sky later.
An Egyptian story
connected with Argo Navis said that it was the ark that carried Isis and Osiris
over the great flood. In India the Hindus thought that the ship did the same
thing but carried Ise and Iswara who were their versions of Isis and Osiris.
Carina is the brightest of the three parts of the old Argo
Navis, its brightest star Canopus is the second brightest star in the sky, but
unfortunately it cannot be seen from Britain. The name Canopus appears to mean
at least according to some references as ‘But of Yesterday’
The Egyptians called the star Kaji Nub which means Golden
Earth, this may refer to the brightness of the star and its nearness to the
horizon. while the general Arabic name is Suhail meaning the Plain. This word
was a personal title in Arabia the symbol of what is brilliant, glorious and
beautiful.
To the Persian astronomers the name Suhail means wisdom and
is seen in their name for the star, Al Anwar I Suhail, which means the Lights
of Canopus. Another Arabic name for the star is Al Fahl or the Camel Stallion.
The Hindus called it Agastya an inspired sage a son of
Varuna, the goddess of the Water. In Sanskrit literature the star is referred
to in its heliacal rising with certain religious festivals. While in China it
was Laou Jin or the Old Man.
Canopus as I have already mentioned is the second brightest star in the sky with a magnitude of -0.7 it is an A class giant star being hotter than the Sun and lies at a distance of 310 light years away.
If Canopus which is 310 light years away was placed at the
same distance as Sirius in Canis Major is to us a mere 8.5 light years then
Canopus would massively outshine the Dog Star.
Canopus is used in navigation by aircraft and space craft.
It is what is referred to as a ‘star-tracker’ the Mariner 4 probe that flew by
Mrs in 1965 and showed that there was no vegetation or life there used Canopus
as a navigation reference point to reach Mars.
Beta or Miaplacidus which means ‘Placid Waters’ is a star of
magnitude 1.7 it’s an A class giant star with a surface temperature of 8,600`C
, making it hotter than our Sun and is 113 light years away.
Epsilon is one of 57 navigation stars that are used by the
RAF. It is 610 light years away; epsilon is a K class giant star and is cooler
than our Sun. The star has a magnitude of 1.9 slightly brighter than the North
Star. Epsioln does not seem to have a name attached to it.
Iota or Aspidiske which means ‘Shield’ which I assume refers
to a shield on the ship the Argo has a magnitude of 2.2 and is an A9 class
supergiant star much hotter than the Sun, it is 690 Light years away. Due to
the wobbling or precession of the Earth Aspidiske will become the South Pole
star in 8100 CE.
Theta has a magnitude of 2.8, it’s a B class star indicating
it is hotter than the Sun. Theta lies at a distance of 460 light years. it is the brightest star in the open star
cluster IC 2602, a cluster with the letters IC stands for Index Catalogue and
was published in 1896 as an addition to the NGC or New General Catalogue which
was produced in 1888. IC 2602 is known as the southern Pleiades, there are
about 75 stars there.
Eta which does not appear to have any Greek or Arabic names
might have been known to the ancient Babylonians Ea or Ia the Lord of the
Waves, while the Chinese knew the star as Tseen She, or Heavens Altarsa .
However, whatever name is given to eta it is a very
remarkable star, it was recorded by Edmund Halley in 1677 as a star or around
magnitude 4.0. During the next 100 years it slowly brightened to about
magnitude 2.0 but then it faded again to magnitude 4.0. In 1820 it rose once
again to magnitude 2.0, then in April 1843 it suddenly brightened to magnitude
-0.8 it outshone every star apart from Sirius. By 1866 it had dropped below
naked eye visibility, it is now around magnitude 4.5. So, what’s going on?
According to theory eta should have destroyed itself with
the massive eruption of 1843 but it didn’t, the theory now is that eta is in
the throes of destroying itself in another massive explosion. Most astronomers
think that eta has one final stage to go through, becoming what is known as a
Wolf-Rayet star.
Wolf-Rayet stars represent a final burst of activity before
a huge star begins to die. It could be tomorrow or within the next 100,000
years which on the cosmic scale is a blink of the eye. These stars, which are
at least 20 times more massive than the Sun, “live fast and die hard”. Their
names come from two French astronomers, Charles Wolf and Georges Rayet, who
discovered the first known star of this kind in 1867. When eta does explode it
will be spectacular!
Eta lies within NGC 3372 or the Carina Nebula, and at a
distance of around 8,500 light years which is sometimes confusingly called the
Eta Carina Nebula, it’s an open cluster containing many other massive very hot
O class stars.
NGC 2516 is an open cluster that is both quite large and
visible to the naked eye. It is located 1,100 light-years from Earth and has
approximately 80 stars, the brightest of which is a red giant star of magnitude
5.2. NGC 3114 is another open cluster approximately of the same size, though it
is more distant at 3,000 light-years from Earth. It is looser and dimmer than
NGC 2516, as its brightest stars are only 6th magnitude.
www.theramblingastronomer.co.uk
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