Download The Argonauts, background to the constellation Carina Argo Navis

The Argonauts, background to the constellation Carina
Argo Navis (or simply Argo) was a very large
constellation in the southern sky that has since been
divided into three constellations. It represented the Argo,
the ship used by Jason and the Argonauts in Greek
mythology. Argo Navis is the only one of the 48
constellations listed by the 2nd century astronomer
Ptolemy that is no longer officially recognised as a
constellation. In 1752, the French astronomer Nicolas
Louis de Lacaille subdivided it into Carina (the keel, or
the hull, of the ship), Puppis (the poop deck), and Vela
(the sails). The constellation Pyxis (the mariner's
compass) occupies an area which in antiquity was
considered part of Argo's mast (called Malus).
The Argonauts were a band of heroes in Greek
Constellation Argo Navis drawn by Johannes Hevelius 1611-87
mythology who, in the years before the Trojan War,
accompanied Jason to Colchis (modern day Georgia) in
his quest to find the Golden Fleece. Their name comes
from their ship, the Argo, which was named after its
builder, Argus. The story goes that, when Jason was 20
years old, an oracle ordered him to head to the Iolcan court
(modern city of Volos) where king Pelias was presiding
over a sacrifice to Poseidon with several neighbouring
kings in attendance. Pelias recognized that Jason was his
cousin and asked him to go and fetch the Golden Fleece for
him. In Greek mythology, the Golden Fleece is the fleece of
a gold-haired winged ram in Colchis. The golden ram's
fleece hung from a tree in the grove of the Colchian Ares,
guarded night and day by a dragon that never slept. King
Pelias swore before Zeus that he would give up the throne
at Jason's successful return with the fleece. Jason took
some 50 of the principal heroes of ancient Greece with him,
amongst them Hercules, Peleus, Orpheus, Castor and Pollux. The story is
of great antiquity – older than Homer (eighth century BC) – and it survives
in various forms, among which many details vary. Some have hypothesized
that the legend of the Golden Fleece was based on a practice of the Black Sea
tribes, who used to place a lamb's fleece at the bottom of a stream to entrap
gold dust being washed down from upstream. This practice is still in use,
particularly in the Svaneti region of Georgia. Anyway, Jason and the
Argonauts were successful in obtaining (stealing?) the golden fleece, after
many struggles (and with the help of king Aeetes’ daughter Medea, who
fell in love with Jason and provided a potion that put the dragon to sleep).
After an epic journey home – much like Homer’s Odyssey – Jason became
king of Thessaly (Aeolia in the Odyssey). But when he, to strengthen his
political ties, married the daughter of the king of Corinth, Medea became
very angry and put curse on Jason and he lost everything. His son,
Thesselaus, became king, and Jason, so the story goes, returned to the old
Argo to rest. As he was sleeping under the bow of the ship it broke apart and fell on him and buried him.
Back to Carina (the Constellation). It contains Canopus, the second brightest star in the night sky, and the
supermassive star eta Carinae which is embedded in the giant Eta Carinae Nebula. Since the Milky Way runs
through Carina, there are also a large number of open clusters in the constellation. These include the "Southern
Pleiades." The most notable object in Carina is Homunculus Nebula (from the Latin meaning Little Man), a
planetary nebula visible to the naked eye believed to have been ejected in an enormous outburst in 1841 which
briefly made Eta Carinae the second-brightest star in the sky. Eta Carinae was once believed to be the Milky
Way's largest star, its mass range from 100 to 150 times the mass of the Sun, with its luminosity about four
million times that of the Sun, but it was recently demoted
to a binary system. It is still big, and gradually
brightening, believed to be not far from becoming a
supernova. NGC 3532, known as the Wishing Well
Cluster, is a large binocular cluster having about 150
stars. Carina also contains the Diamond Cross, which is
larger than the Southern Cross, and from the perspective
of the southern hemisphere viewer upside down, the long
axes of the two crosses being close to parallel, and the
naked-eye globular cluster NGC 2808. Epsilon Carinae
and Upsilon Carinae are double stars visible in small
telescopes. Carina also is the radiant of the Eta Carinids
Keyhole Nebula, imaged by Hubble Space
meteor shower, which peaks around January 21 each year.
Telescope. The small nebula to the upper left has
Eta Carinae's effects on the nebula can be seen directly:
been nicknamed "finger of God" or "God's birdie",
The dark globules in the image and some other less visible
due to the gesture it appears to be making
objects have tails pointing directly away from the
massive star.
A portion of the Carina Nebula is known as the Keyhole
Nebula, a name given to it by John Herschel in the 19th
century. The Keyhole Nebula is actually a much smaller
and darker cloud of cold molecules and dust, containing
bright filaments of hot, fluorescing gas, silhouetted
against the much brighter background nebula. The
diameter of the Keyhole structure is approximately 7
light years.
Johann Bayer in 1603 created a stellar designation in
which a specific star in a constellation is identified by a
Greek letter, starting with alpha for the brightest, beta for
the second brightest and so on. After the constellation
Argo Navis was broken up in 1752 by de Lacaille into
Carina, Vela, and Puppis, these Greek-letter designations
were kept, so that Carina does not have a full sequence of Greek-letter designations. For example, since Argo
Navis's gamma star went to Vela, there is no gamma Carinae. The Kepler spacecraft has identified eight stars in
Carina with transiting exo-planets, varying in distance of 100 to 12,000 light years from us.
AK
Carina nebula (NGC 3372). Eta Carinae and its surrounding Homunculus Nebula are the small, saturated (white) blob centred
vertically in the image and approximately 1/5 of the distance from left to right. The Finger of God. Mystic Mountain. Taken by HST