OphiuchusOphiuchus
Particulars:
General:
One of the larger constellations located in the equatorial
regions of the sky. To the north Ophiuchus is neighboured
to Hercules. On the western border one finds one
part of the constellation Serpens, Serpens
Caput (head of the snake). Libra and Scorpius,
which also covers the complete southern border. To the east it is
flanked by Sagittarius (south) and the second
part of Serpens (north), Serpens Cauda
(tail of the snake). It streches from DECL= +14 degrees to
DECL=-30 degrees and roughly from RA=16h to RA=18h 40m.
From Hercules through Ophiuchus to is south-east
border and beyond the background of the stars increase
significantly. Random gazing is just a joy.
Although this constellation is not part of the zodiac the sun
passes through Ophiuchus in December each year. When the
zodiac first was invented by the Babylonians 3000 years ago, the
sun just passes through the twelve constellations to which we
still refer as the zodiac. Due to the precession of the Earth the
apparent way of the sun through the sky has changed through the
milleniums.
Stars and objects
After the triple system of alpha Centauri Barnard's
Star (named after Edward E. Barnard, the discoverer of
this star), a red dwarf of 9.5 mag, is the next closest star to
us lying in a distance of about 6 light years. Although it is
quite faint it is within the reach of small telescopes and well
worth being observed. Its proper motion is with one degree each
350 years the largest of all stars in the sky. This object is one
of the candidates which may have a planetary system. At least
there are indications that there could be a planet of the size of
Jupiter. Please find more information on one of the following
pages:
The binary tau Oph is not easy to split. The two 5th
and 6th mag main sequence stars (F2 and F5) require scopes with
an aperture of at least 100 mm and high magnification for
separation. The two stars revolve each other with a period of 224
years.
Nearly the same technical support is required to split 70 Oph,
a close but wonderful consisting of an yellow and an orange star
of 4th and 6th magnitude. The binary has a revolution period of
87.7 years and lies just about 17 light years distant..
Another quite difficult double is 68 Oph. The components
are of 4.4 mag and 9.2 mag.This star is associated with some
meteor showers.
Even more difficult is 73 Oph. Scopes with an aperture of
at least 250mm will be necessary to split it into its components
which revolve each other each 423 years.
The double 36 Oph can be viewed with small scopes. It
consists of two orange stars of 5th magnitude.
Rho Oph (north of Antares (alpha Sco)) is a nice multiple
star system. Small telescopes reveal two B stars of 5.02 mag and
5.92 mag, repsectively. At each side of the stars a companion of
8th mag can be spotted. These four stars form a V-shaped group. Rho
Oph itself is embedded in a nebulosity, IC 4604. The
nebulosity is quite faint with dark lanes and an interesting
stellar background. IC 4604 and can only be made visible
on long-exposure photographs.
On September 9th 1604 has been observed in Ophiuchus. By
this time the brightness of V 843 (the star which went to
supernova) was already higher than any other star in the sky.
Eight days later Kepler saw this supernova and started a detailed
study of the object. Its nowadays called Keplers Supernova.
The planetary nebula NGC 6572 belongs to the most
interesting planetaries. The nebula itself shows up as a bright
oval disk, but in this region there are several nebulous clusters
which make NGC 6572 well worth observing.
The open star cluster IC 4665 is an easy object to
observe. Quite in the field of beta Oph a binocular shows
about 20 stars of 7th mag and fainter scattered over an area of
about 1 degree.
A larger object but still easy to view is NGC 6633. This
cluster has more than 60 members.
There are a good amount of globular clusters in this
constellation:
With a distance of about 5500 light-years M 9 (NGC 6333)
belongs to the nearer globular clusters. Interstellar dust is
dimming the light of this 7th mag cluster at the north-western
edge.
The globular clusters M 10 (NGC 6254) and M 12 (NGC
6218) are the most prominent of the visible globulars in Ophiuchus.
Both can be spotted with the naked eye; Binoculars or small
scopes are sufficient to resolve them as misty patches. M 12
is a bit larger, yet fainter than M 10 which form is more
condensed.
A globular with a lesser condenced center is M 14. The
shape appears slightly elliptical.
M 19 (NGC 6273) is the most oblate known globular cluster.
Its about 27 thousand light years from earth yet only about 4600
light years distant to the Galactic Center.
Even closer to the Galactic Center is M 62, which shows a
highly irregular shape (in fact, it is the most irregular shaped
globular cluster we know of). These last two globular clusters
well deserve telescopic observation.
M 107 shows something unusual for globular clusters: it
contains some dark regions. Its smaller and fainter than M 10
or M12.
NGC 6356 is in the area of M 9; yet it is a bit
faint.
The meteor shower Ophiuchids can be seen from May 19th to
July 2nd. The maximum of the shower activity occurs on June 20th.
The meteors are usually fainter than 3 mag.
From April 8th to June 16th the northern May Ophiuchids
are activ. The maximum is mit 2 to 3 meteors between May 18 and
May19th.
Another stream with a long duration is the southern May
Ophiuchides extending from April 21st to June 4th. Between
May 13th and May 18 the maximum of the shower activity occurs.
The Theta Ophiuchids can be observed from May 21st till
June 16. The Maximum of the shower activity is not very
remarkable lying somewhere around the 10th of June.
Mythological Background:
There are several stories who Ophiuchus is thought to
represent:
He might be King Karnabon of Seythia. Ceres gave order to
Triptolemus to teach humanity in how to grow grain. King Karnabon
showed friendly hospitality when Triptolemus came to him, but
after a short while he changed his attitude completely and tried
to kill Triptolemus. To prevent his flight Karnabon killed the
dragon which pulled the wagon of T. Yet Ceres sent immediately
another dragon and let Karnabon kill himself. To keep the memory
of his cruelity alive she placed him next to the dragon on the
sky (Hyginus, Astron. lib.II.c.14)
On the other hand there is a story that Ophiuchus is
Hercules, slaing a giant snake near the river Sagaris in Lybia.
He is also thought to be Triopas, who destroyed a temple of
Ceres. He was punished with hunger and finally with even that
snake (or dragon) clinching him permanently (Ap. Hyginus,
Poeticon Astronomicum l.II.14).
Some see him for Phorbas who had slain that very dragon on the
island Rhodos (Polyzelos Rhodius ap. eumd.l.c.)
Another story gives him as Aeskulapius, healing and revitalising
Glaukus, son of Minos, after he was bitten by a snake (Hyginus
l.c.Cf. Erastothenes Catasterismi 6).