Boötes

Boötes ( /boʊˈoʊtiːz/) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from the Greek Βοώτης, Boōtēs, meaning herdsman or plowman (literally, ox-driver; from boos, related to the Latin bovis, “cow”). The "ö" in the name is a diaeresis, not an umlaut, meaning that each 'o' is to be pronounced separately.

Boötes was one of the 48 constellations described by the 2nd century astronomer Ptolemy and is now one of the 88 modern constellations. It contains the third brightest star in the night sky, Arcturus.

Notable features

Stars

τ Boötis, a relatively Sun-like star, is orbited by the massive hot Jupiter planet τ Boötis Ab. It was the fourth extrasolar planet to be discovered and is one of the most studied. Unusually, Tau Boötis is a tidally locked to its planet. Boötes also hosts a large number of double stars suitable for viewing by amateur astronomers.

Named stars

Deep-sky objects

• NGC 5466 is a loose globular cluster that can be observed with most telescopes. It was discovered by William Herschel on May 17, 1784.
• The Boötes void, a large section of the universe devoid of galaxies, is located in the area of Boötes.
• The Boötes Dwarf Galaxy (Boo I dSph) is a faint, satellite galaxy of the Milky Way located in Boötes about 197 000 light-years (60 kpc) away from Earth.

History

The former constellation Mons Maenalus, created by Johannes Hevelius, resided in the southern part of Boötes. It contained only faint stars barely visible to the naked eye.

Mythology

In ancient Babylon the stars of Boötes were known as SHU.PA. They were apparently depicted as the god Enlil, who was the leader of the Babylonian pantheon and special patron of farmers.^[2]

Exactly whom Boötes is supposed to represent in Greek mythology is not clear. According to one version, he was a ploughman who drove the oxen in the constellation Ursa Major using his two dogs Chara and Asterion (from the constellation Canes Venatici). The oxen were tied to the polar axis and so the action of Boötes kept the heavens in constant rotation.

Boötes was also supposed to have invented the plough. This is said to have greatly pleased Ceres, the goddess of agriculture who asked Jupiter to give Boötes a permanent fixture in the heavens as a reward for doing this.

Another version portrays Boötes as a grape grower called Icarius, who one day invited the Roman god Bacchus, also called Dionysus, to inspect his vineyards. Bacchus revealed the secret of wine making to Icarius, who was so impressed by this alcoholic beverage that he invited his friends round to sample it. Having never tasted wine before, they all drank too much and woke up the next morning with terrible hangovers; and they made the mistaken assumption that Icarius had tried to poison them. It was decided that Icarius should pay the price with his own life, and he was swiftly murdered in his sleep. Bacchus placed Icarius in the stars to honor him.

Following another reading the constellation is identified with Arcas, son of Zeus and Callisto. Arcas was brought up by his maternal grandfather Lycaon, to whom one day Zeus went and had a meal. To verify that the guest was really the king of the gods, Lycaon killed his grandson and prepared a meal made from his flesh. Zeus noticed and became very angry, transforming Lycaon into a wolf and gave back life to his son. In the meantime Callisto had been transformed into a she-bear, by Zeus' wife, Hera, who was angry at Zeus' infidelity. When he was grown up, Arcas met with the she-bear and, since obviously he didn't recognize her as his mother, he began to chase Callisto. Callisto, followed by Arcas, sheltered herself in a temple, a sacred place whose profaners were convicted to death. To avoid such fate, Zeus decided to set them in the sky, Arcas as Boötes and Callisto as Ursa Major. This is a rare version of the myth surrounding Ursa Major, as the myth usually holds that Arcas is transformed into a bear as well (becoming Ursa Minor), and in such versions Boötes has no part. Ursa Minor, and Ursa Major, are constellations whose identification only originated in later classical Greece, and in Rome, and as such Boötes kept separate associations dating from much earlier.

In Ovid's Metamorphoses VIII, Icarus is told by his father Daedalus, upon receiving the wings, to fly using the Boötes and Orion as guides. Icarus ignores the advice to run this "middle path" and subsequently drowns.

Visualizations

Illustrations of Boötes traditionally represent him as a herdsman with a club or staff, holding two hunting dogs on a leash and following Ursa Major around the pole.

H.A. Rey has suggested an alternative way to visualize the herdsman, in which he is seated and smoking a pipe.^[3] The stars ε Boo, δ Boo, μ Boo, β Boo, γ Boo, ρ Boo, and σ Boo form the herdsman's head. In addition, the stars δ Boo, μ Boo, and β Boo may be seen to form a cap. The stars γ Boo, λ Boo, θ Boo, and κ Boo form the herdsman's pipe. Star γ Boo is of the third magnitude and would be the herdsman's mouth. Stars ε Boo, ζ Boo, and α Boo (Arcturus) form the herdsman's body. Star ε Boo is of the third magnitude whereas Arcturus is of magnitude zero. Stars α Boo, η Boo and υ Boo form the herdsman's leg, with η Boo being the knee. Finally, stars υ Boo and τ Boo form the herdsman's foot. Star η Boo is of the third magnitude.

Modern diagrammatic visualizations often depict Boötes as looking like a kite.^[4]

Equivalents

In Chinese astronomy, the stars of Boötes are located in three areas: the Purple Forbidden Enclosure (紫微垣 Zǐ Wēi Yuán) and Heavenly Market Enclosure (天市垣 Tiān Shì Yuán) (both included in the Three Enclosures (三垣, Sān Yuán)), and the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng).

Namesakes

The US Navy ship USS Bootes (AK-99) was named after the constellation.

References

External links

• The Deep Photographic Guide to the Constellations: Bootes
• WIKISKY.ORG: Boötes
• Star Tales – Boötes

Coordinates: 15^h 00^m 00^s, +30° 00′ 00″