DracoDraco
Abbreviation:
Particulars:
General:
A quite extended constellation of the northern hemisphere. The
four stars forming the dragons head (beta Dra, gamma Dra, xi
Dra and nu Dra), build a conspicuous asterism called
the Lozenge. Draco belongs to the few
constellations which really resemble the object they were named
after.
The northern boundary reaches higher than DECL=+80 degrees, the
southern border streches along DECL=+50 degrees; to the east and
the west it extends from RA=10h to RA=20h. It looks like Draco
is encircling the Little Bear, Ursa Minor.
Long time ago, about 3500 years B.C., alpha Dra, also
called Thuban (arab. meaning 'the dragon'), has
been the Pole Star.
Stars and other objects
Epsilon Dra is a good double to be observed with scopes
at a moderate magnification. Its companions are about 3 arc sec
apart.
The binary mu Dra is a good test for a scope with an
aperture of 60mm. Good optics might split that pair consisting of
two F7 main sequence stars (5.83 mag and 5.80 mag).
An outstanding binary is nu Dra. The two white stars (an
A6V and an A4m) have magnitudes of 4.88 and 4.87. They are a good
object for binoculars.
Small scopes reveal the 8th mag blue companion of the
G9IIIbCN-0.5 star omicron Dra (4.66 mag).
A good binocular may be sufficient to split the pair of psi
Dra. Small scopes show a 5th mag star and a 6th mag star.
Another easy pair for small telescopes is 40-41 Dra. The
two yellow stars are of 6th mag. Its coordinates are roughly
RA=18h and DECL=+80 degrees.
A really impressive triple system is 39 Dra. Field glasses
show a wide double; in larger scopes a third star close to the
brighter one occurs.
Another attractive triple is 16-17. In binoculars two
blue-white stars of 5th mag are revealed. Viewing with a
telescope shows another star of 7th mag close to one of the first
two.
At a magnitude of 8.8, the planetary nebula NGC 6543 is
one of the brightest in the sky. It was the first planetary
nebula to be observed with a spectroscope; the observers were
surprised to find emission lines in the spectrum of this object.
This started the controversy whether planetaries are numerous
stars or, as it turned out to be, clouds of diffuse gas. A small
telescope (about 70 to 80 mm aperture) shows a foggy blue-green
disk; more powerful scopes are required to reveal the internal
structure: a bright irregular helix. Since NGC 6543 is a
circumpolar object for most observers, you can view it throughout
the year. It can be found half way between delta Dra and zeta
Dra (RA=18h is closely running through it).
The quasar 3C 351 lies at RA=17h, DECL=+60 deg. It has a
brightness of 15.3 mag and shows a redshift of .371 in its
spectrum. This yields a distance of about 7 billions (7*10^9)
light-years.
From October 6th to October 10th the meteor shower of the Draconids
is active; this shower is associated with the comet Giacobini-Zinner
and has a sharply defined maximum on October 9th.
In the midth of January the shower January Draconids seems
to be active. There are only few hints for the existence of this
shower.
The Eta Draconids take place from March 22nd to April 8th.
The maximum occurs between March 29th and March 31st.
Between March 13th and April 17th the meteor shower of the Tau
Draconids can be observed. The maximum occurs around the end
of March.
There is only little evidence for the showers of the September
Eta Draconids and the Omicron Draconids . Detailed
information about all meteor showers, their strength and their
orbits can be found the database about meteor shower from Gary
Kronk.
Mythological Background:
This constellation is associated with the dragon slain by
Cadmus, the brother of Europa. The father sent Cadmus to find
Europa who was kidnapped by Zeus. But though he searched for his
sister everywhere he could not find her. Because his father has
threatened him not to come back if he failed, he left the country
and search for help at the oracle of phoebus. The spell of the
oracle send him to a far away place where a terrible monster, a
dragon, lived, who killed all the men Cadmus had with him. After
he successfully killed that dragon, the goddess Athena instructed
him to plant some of the teeth of the dragon. Surpised Cadmus
obeyed the goddess and the miracle happened: Armed men grew from
the soil; Cadmus, afraid of the new enemy, started to lift his
armes, when these people told him not to interfere their internal
fights. Immediately they start to fight each other. All but five
died and these five helped Cadmus to build a new city. This city
was the famaous city called Thebes.
(This story can be found in "Metamorphoses, III" by the
latin poet Publius Ovidius Naso (43 BC - 17 AC).)