Ophiuchus

Ophiuchus

Constellation
List of stars in Ophiuchus
Abbreviation	Oph
Genitive	Ophiuchi
Pronunciation	/ˌɒfiːˈjuːkəs/ Óphiúchus, genitive /ˌɒfiːˈjuːkaɪ/
Symbolism	the snake-holder / the healer
Right ascension	17 h
Declination	−8°
Quadrant	SQ3
Area	948 sq. deg. (11th)
Main stars	10
Bayer/Flamsteed stars	62
Stars with planets	7
Stars brighter than 3.00m	5
Stars within 10.00 pc (32.62 ly)	11
Brightest star	α Oph (Ras Alhague) (2.08m)
Nearest star	Barnard's Star (5.98 ly, 1.83 pc)
Messier objects	7
Meteor showers	Ophiuchids Northern May Ophiuchids Southern May Ophiuchids Theta Ophiuchids
Bordering constellations	Hercules Serpens Libra Scorpius Sagittarius Aquila
Visible at latitudes between +80° and −80°. Best visible at 21:00 (9 p.m.) during the month of July.

Ophiuchus is a large constellation located around the celestial equator. Its name is Greek (Ὀφιοῦχος) for 'snake-holder', and it is commonly represented as a man grasping the snake that is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It was formerly referred to as Serpentarius (/ˌsɜrpənˈtɛəriəs/), a Latin word meaning the same as its current name.

Location

It is located between Aquila, Serpens and Hercules, northwest of the center of the Milky Way. The southern part lies between Scorpius to the west and Sagittarius to 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.

Notable features

The constellation Ophiuchus as it can be seen by naked eye. AlltheSky.com

Stars

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

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.^[1]

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 of Taurus Poniatovii, Poniatowski's Bull.)

In 2005, astronomers using data from the Green Bank Telescope discovered a superbubble so large that it extends beyond the plane of the galaxy.^[2] It is called the Ophiuchus Superbubble.

In April 2007, astronomers 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.^[3]

The supernova of 1604 was first observed on October 9, 1604, near θ Ophiuchi. Johannes Kepler saw it first on October 16 and studied it so extensively that the supernova 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' 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.^[4]

In 2009 it was announced that GJ 1214, a star in Ophiuchus, undergoes repeated, cyclical dimming with a period of about 1.5 days consistent with the transit of a small orbiting planet ^[5]. Further, the authors conclude that the planet must have a low density consistent with vast quantities of water. The proximity of this star to Earth (42 light years) makes it a tempting target for further astronomic observations.

In April 2010, the naked-eye star ζ Ophiuchi was occulted by 824 Anastasia.

Deep-sky objects

Ophiuchus contains several star clusters, such as IC 4665, NGC 6633, M9, M10, M12, M14, M19, M62, and M107, as well as the nebula IC 4603-4604. The unusual galaxy merger remnant NGC 6240 is also in Ophiuchus. In 2006, a new nearby star cluster was discovered associated with the 4th magnitude star Mu Ophiuchi.^[6] The Mamajek 2 cluster appears to be a poor cluster remnant analogous to the Ursa Major Moving Group, but 7 times more distant (approximately 170 parsecs away). Mamajek 2 appears to have formed in the same star-forming complex as the NGC 2516 cluster roughly 135 million years ago.^[7]

Mythology

Ophiuchus holding the serpent, Serpens, as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Above the tail of the serpent is the now-obsolete constellation Taurus Poniatovii while below it is Scutum.

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 close 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 Agesander, Athenodoros, and Polydorus 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 Thessalonian 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.

Astrology

Ophiuchus is not included in standard astrological zodiacs, which divide the ecliptic into abstract 30-degree segments (implying exactly 12 signs) rather than using the physical constellations. However, a few astrologers using a sidereal zodiac use it as the 13th zodiacal sign.

Citations

by DB

References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

• Media related to Ophiuchus at Wikimedia Commons
• The Deep Photographic Guide to the Constellations: Ophiuchus
• Star Tales – Ophiuchus

Coordinates: 17^h 00^m 00^s, +00° 00′ 00″