Saturday, January 3, 2009

Ophiuchus (Ὀφιοῦχος IPA: /ˌɒfiːˈjuːkəs/) is a large constellation located around the celestial equator

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Ophiuchus
Ophiuchus
Click for larger image
List of stars in Ophiuchus
Abbreviation:Oph
Genitive:Ophiuchi
Symbolism:the snake-holder / the healer
Right ascension:17 h
Declination:
Area:948 sq. deg. (11th)
Main stars:10
Bayer/Flamsteed
stars:
62
Stars with
known planets:
4
Bright stars:5
Nearby stars:8
Brightest star:α Oph (Ras Alhague) (2.1m)
Nearest star:Barnard's Star (5.96 ly)
Messier objects:7
Meteor showers:Ophiuchids
Northern May Ophiuchids
Southern May Ophiuchids
Theta Ophiuchids
Bordering
constellations:
Hercules
Serpens Caput
Libra
Scorpius
Sagittarius
Serpens Cauda
Aquila
Visible at latitudes between +80° and −80°
Best visible at 21:00 (9 p.m.) during the month of July

Ophiuchus (Ὀφιοῦχος IPA/ˌɒfiːˈjuːkəs/) is a large constellation located around thecelestial equator. Its name is Greek for 'snake-holder', and it is commonly represented as a man grasping the snake that is represented by the constellationSerpens. Ophiuchus was one of the 48 constellations listed by the 1st centuryastronomer Ptolemy, and it remains one of the 88 modern constellations. It was formerly referred to as Serpentarius (/ˌsɚpənˈtɛəriəs/), a Latin word meaning the same is its current name.

Ophiuchus is a zodiacal constellation (meaning that the Sun passes through it during the course of the year), but unlike the other twelve, it is not counted as anastrological sign by astrologers. As of 2008, the sun passes through Ophiuchus between November 30th and December 17th.[1]

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[edit]Location

It is located between AquilaSerpens and Hercules, northwest of the center of theMilky Way. The southern part lies between Scorpius to the west and Sagittariusto the east. It is best visible in the northern summer and located opposite Orion in the sky. Ophiuchus is depicted as a man grasping a serpent; the interposition of his body divides the snake constellation Serpens into two parts, Serpens Caput and Serpens Cauda, which are nonetheless counted as one constellation.

Johannes Kepler's drawing depicting the location of the stella nova in the foot of Ophiuchus.

[edit]Notable features

[edit]Stars

The brightest stars in Ophiuchus include α Ophiuchi, called Rasalhague (at the figure's head), and η Ophiuchi.

RS Ophiuchi is part of a class called recurrent novae, whose brightness increase at irregular intervals by hundreds of times in a period of just a few days. It is thought to be at the brink of becoming a type-1a supernova.[2]

Barnard's Star, one of the nearest stars to the Solar System (the only stars closer are the Alpha Centauri binary star system and Proxima Centauri), lies in Ophiuchus. (It is located to the left of β and just north of the V-shaped group of stars in an area that was once occupied by the now-obsolete constellation ofTaurus Poniatovii, Poniatowski's Bull.)

In 2005, astronomers using data from the Green Bank Telescope discovered asuperbubble so large that it extends beyond the plane of the galaxy.[3] It is called the Ophiuchus Superbubble.

In April 2007astronomers announced that the Swedish-built Odin satellite had made the first detection of clouds of molecular oxygen in space, following observations in the constellation Ophiuchus.[4]

The supernova of 1604 was first observed on October 91604, near θ Ophiuchi.Johannes Kepler saw it first on October 16 and studied it so extensively that thesupernova was subsequently called Kepler's Supernova. He published his findings in a book titled De stella nova in pede Serpentarii (On the New Star in Ophiuchus's Foot). Galileo used its brief appearance to counter the Aristotelian dogma that the heavens are changeless.

In approximately 40,000 years Voyager 1 probe will pass within 1.6 light years of the star AC+79 3888, which is located in Ophiuchus.[5]

[edit]Deep-sky objects

Ophiuchus contains several star clusters, such as IC 4665NGC 6633M9M10M12M14M19,M62, and M107, as well as the nebula IC 4603-4604. The unusual galaxy merger remnant NGC 6240 is also in Ophiuchus.

[edit]Mythology

There exist a number of theories as to whom the figure represents.

The most recent interpretation is that the figure represents the healer Asclepius, who learned the secrets of keeping death at bay after observing one serpent bringing another healing herbs. To prevent the entire human race from becoming immortal under Asclepius' care, Zeus killed him with a bolt of lightning, but later placed his image in the heavens to honor his good works. It has also been noted that the constellation Ophiuchus is in close proximity in the sky to that of Sagittarius, which has at times been believed to represent Chiron (the mentor of Asclepius and many other Greek demigods), though Chiron was originally associated with the constellation Centaurus.

Another possibility is that the figure represents the Trojan priest Laocoön, who was killed by a pair of sea serpents sent by the gods after he warned the Trojans not to accept the Trojan Horse. This event was also memorialized by the sculptors AgesanderAthenodoros, andPolydorus in the famous marble sculpture Laocoön and his Sons, which stands in the Vatican Museums.

A third possibility is Apollo wrestling with the Python to take control of the oracle at Delphi.

A fourth is the story of Phorbas, a Thessalonikan who rescued the people of the island of Rhodes from a plague of serpents and was granted a place in the sky in honor of this deed.

[edit]Astrology

Although Ophiuchus intersects the ecliptic, it is not a zodiacal sign in most versions of astrology. The signs are defined as more-or-less 30-degree segments of the ecliptic, of which there are twelve, and they are named after nearby constellations at the time the system was developed, rather than being defined by the modern constellations. However, a few sidereal astrologers consider the sun to be in the sign Ophiuchus when it is in the constellation Ophiuchus, which as of 2008 is November 30 to December 17.

[edit]Citations

[edit]References

[edit]External links

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