Ophiuchus , also named the Serpent eater , is a Constellation of the northern Hemisphere. Representing a man carrying a snake with end of arm, the Serpentaria divides the constellation of the Serpent into two parts: the head and the tail.

History

Ophiuchus is an old constellation. It was indexed with 47 other constellations by Ptolémée in its Almageste and was sometimes called Serpentarius , the serpent eater.

The constellation represents a man carrying a snake around him; Ophiuchus precisely divides the constellation of the Serpent into two parts. It would represent Asclépios, the legendary doctor . Asclépios would have killed one day a snake and would have had the surprise to see another snake reviving it with grasses. The medical knowledge of Asclépios would have grown thereafter at the point where it was capable of ressusciter deaths. This worried Hadès, god of the Enfers, who feared not to receive hearts more. As convainquit it his/her brother Zeus to strike down it and issue as all the mortals must die one day. In order to honor its talents with healer, Zeus placed it with its snake in the skies.

It is not however very easy to distinguish there the figure of a man without showing a little imagination.

The most significant object of the constellation of Ophiuchus was the Supernova whose explosion was visible the October 10th 1604, close to θ  Ophiuchi. It was observed by Johannes Kepler, from where its Star name “of Kepler”. Galileo used his short appearance to counter the dogma aristotelician which indicated that the skies never change.

Ophiuchus was also the theater of two novae in 1848 and 1917.

Astrology

Crossed by the Sun of the November 30th to the December 17th, it is however not counted in the traditional Zodiaque of the Astrologie.

The constellation of Ophiuchus was extended towards the south by a decision of UAI in 1922, and is now in the plan of the ecliptic , which means that the trajectories of the Sun, but also of the Planet S and the the Moon cross it. That was not the case when the Zodiaque was created it there 2 or 3.000 years.

Traditionally, unlike the other constellations crossed by the ecliptic, Ophiuchus is however not counted among the twelve signs of the Zodiaque. It is about the one of the differences occurring between the signs of the zodiac, in particular used in Astrologie, and real displacements of the celestial objects in the Constellation S.

One should not confuse the constellations zodiac (of which Ophiuchus forms now part) and the signs of the zodiac, arbitrary zones of 30° counted starting from the vernal Point and who are used for the astronomical locations. The argument consisting in saying that " the zodiac has in fact 13 signes" is fallacious, because neither the astronomers nor the astrologers never measured planetary displacements while being based on the constellations (well too vague for this employment).

See also: Zodiac

Observation of stars

; Localization of the constellation Ophiuchus does not have a very prominent star: Rasalhague, its principal star, is magnitude 2, and the remainder of the constellation takes shape between 3 and 4. These stars are thus used for to check local alignments, but are not " phares" immediately locatable like are the neighbors α Bootis (Arcturus) with the west, α Lyrae (Vega) with north, α Aquilae (Altaïr) with the east, or α Scorpii (Antarès) in the south.

All in all, Ophiuchus is located on alignment between α Scorpii (at the lower edge of the figure) and α Lyrae (10° except figure, more in North). This arc of 60° passes close to Rasalhague about in its medium, with 30° from these two " phares".

In the other direction, Ophiuchus and the Tête of the Snake contain four stars relatively more brilliant in alignment between α Bootis and the “neck” of the Sagittarius, Nunki (σ Sgr), alignment which passes by the top of the arc of the Sagittarius and is prolonged more in the South towards Fomalhaut.

; Form constellation The constellation does not resemble large - thing and it is necessary to make a large effort of imagination to see there a silhouette of man or a kind of catch.

Rasalhague (α Oph) is at the Northern top of an equilateral triangle (β Oph in the East, κ Oph in the East), which appears the “head”. The “body” is a rather regular but not very suggestive rectangle, delimited by the base of this triangle (β and κ Oph) and two appreciably parallel stars (ν and ι Oph) located in lower part, on alignment α Bootis - Nunki (σ Sgr). The small star couple in the West (ε and δ Oph) form the hand which holds the Tête of the Snake, whose limit passes immediately to the West.

East coast, although located in a very convincing alignment with its two neighbors of the Tail of the Snake, the star located in alignment Rasalhague (α Oph) towards (β Oph) is ν Oph, it marks the South-eastern limit of the constellation.

Principal stars

See also: List of stars of Ophiuchus

Rasalhague (α  Ophiuchi)

Rasalhague (α  Ophiuchi) is the most brilliant star of the constellation. It is a white-blue star of type located at 47 light-years. Its Magnitude connects is of 2,08, it shines 26 times more than the Sun, which gives him a absolute Magnitude of 1,3.

It has small a distant companion of 7 ua which Orbite in 8,7 years.

Other stars

Ophiuchus is an old and rather brilliant constellation. Consequently, a certain number of its stars bear a proper name: Cebalrai (β  Oph), Yed Prior (δ  Oph) and Yed Posterior (ε  Oph), Sabik (η  Oph) and Marfik (λ  Oph).

Marfik, Sabik and 67  Oph are double stars. 70  Oph is a triple star. ρ  Oph is a quadruple star.

U  Oph is a Binaire with eclipses of the family of Algol (β  Persei). Distant 1.500 years lights, its two components are blue giants who occult themselves every 1,7 days, cause a drop in the magnitude of the whole a little less than one magnitude.

Y  Oph is a variable star Céphéide, of which the magnitude passes from 5,90 and 6,40 over one 17,13 days period.

RS Ophiuchi, a star too not very luminous to interest the astronomer amateur, fact part of the very strange class of the “recurring novas”, whose brightness can grow in an unforeseeable way several hundreds of times in the space of a few days.

star of Barnard, 4th star more near to Solar system (2nd if one regards the system of Alpha of the Centaur as only one member), is in Ophiuchus. It is distant 5,96 years light. It is about a Naine red magnitude connect 9,54.

Celestial objects

Ophiuchus contains globular Amas enormously S, such M9, M10, M12, M14, M19, M62 and M107, the open Amas S NGC 6633 and IC 4665, the Nébuleuse S IC 4603 - 4604, the Nébuleuse planet gear NGC 6572, the Nébuleuse of the Butterfly m2-9 which is a symbiotic star and Barnard 68, a dark cloud of dust. The 1e " there was discovered; system of double planète" , that is to say two planets which do not revolve around a star: Oph 162225-240515 .

See too

• List of stars of Ophiuchus

Simple: Ophiuchus

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