|Number of Bright Stars||3|
|Brightest Star||α Boo|
|Meteor Shower||January Bootids / June Bootids / Quadrantids|
|Adjoining Constellations||Virgo, Ursa Major, Canes Venatici .etc.|
|Optimal Observational Duration||May~June|
|Optimal Observational Dimension||+90°~-50°|
|Fully visible region||90°N~35°S|
Boötes is one of the 88 constellations in the sky, located north-east of Virgo, about 30 degrees wide and 50 degrees high. It is one of 88 modern constellations, and one of 48 constellations described by Ptolemy (the astronomer in second century).
Boötes contains the fourth brightest star in the night sky: the orange giant Arcturus. Boötes is also home to many other bright stars, including eight brighter than magnitude 4 and 21 brighter than magnitude 5, for a total of 29 stars easily visible to the naked eye.
We can divide Boötes into two parts: Arcturus with the stars in east west, and many pentagonal stars in the north.
The Origin of Boötes
The name of Boötes comes from the Greek Βοώτης，which means a shepherd or a famer (the lexicial meaning is “ox driver”, cognate with the Latin “bovis”).
In the Latin name Boötes, “ö” is a dieresis, which means that each “o” should be pronounced individually.
Appearance of Boötes
Boötes is a constellation in the northern sky. Its position on the celestial sphere spans from 0° to +60° of declination, from 13 to 16 hours of right ascension.
Boötes is made up of several moderately bright stars, forming a pentagon shaped like a large kite. The brightest star in this constellation is Arcturus (apparent magnitude -0.04m), which looks like a light hanging under the kite. Arcturus is one of the three brightest stars in the northern sky (the other two are Vega and Capella). Ancient Greeks called it “the most beautiful one of all stars.”
The ancient Greeks imagined the star map of Boötes as a fierce hunter, holding a spear in his right hand and raising his left hand, eager to seize the big Bear in front of him. In late spring and early summer, Boötes is at the zenith of the sky.
Globular Clusters and Galaxies
Boötes is a constellation far from the galactic disc in the celestial sphere, so there are no open star clusters and nebulae, but many bright globular clusters and dim galaxies in it.
The brightness of globular cluster NGC 5466 exceeds 9.1, and its apparent diameter is 11 angular seconds. It is a cluster with a very loose structure and only a few stars, so it looks like an open cluster with a very large number of stars under the telescope. NGC 5466 belongs to the loosest 12th grade in Sharpley-Sawyer concentration classification, which reflects its unconcentrated nature.
The apparent diameter of NGC 5466 is large, which obviously leads to its low surface brightness, so its brightness looks far lower than 9.1 marked in the catalog, and it needs a large amateur astronomical telescope to watch it. Ordinary amateur telescopes can only see more than ten stars.
NGC 5248 (Caldwell 45) is divided into Sc-type galaxies (spiral galaxies with relaxed spiral arms) in the Hubble Sequence, with apparent magnitude of 10.2 and apparent diameters of 6.5 and 4.9 angular seconds.
NGC 5248 is 50 million light-years away from the earth, and is a member of the galaxy cluster of Virgo. The outer edge of its spiral arm is dim, and the ionized hydrogen region, dust belt and young stars can be seen.
Other galaxies like NGC 5676 (Sc-type, apparent magnitude 10.9, apparent diameters of 3.9 and 2.0 angular seconds), NGC 5008 (Sc-type emission line galaxy), NGC 5548 (one of the Seyfert galaxies) and so on are also the focus of many attention.
Bootes Void is a huge empty space without galaxies, with 250 million light-years in diameter. It is 700 million light-years away from Earth, which discovered by Robert Kirshner and his colleagues in 1981. There are two super clusters at the boundary behind this hole, which are about 830 million light-years and 1 billion light-years away from the Earth respectively.
Quadrantids (QUA) is one of the meteor showers with the largest number of meteors. It was discovered in January 1853 and named by Alexander Stewart Herschel, grandson of William Herschel in 1864.
The radiation point of QUA is in Bootes, close to κ Boo. The previous name of it was Quadrans Muralis. In 1920, Quadrans Muralis was merged into Bootes by the International Astronomical Union.
Meteors in QUA are all very dim, but during the maximum in 3th and 4th January, the number of meteors per hour is about 100. The peak of Quadrantids is at about 130 meteors per hour on the zenith. It is also a very narrow meteor shower in apparition. Quadrantids are notoriously difficult to observe because of their low radiation and bad weather.
On April 28th, 1984, visual observer Frank Witte observed a remarkable outbreak in Arcturus, which was usually calm from 00:00 to 2:30. Through his 6 cm telescope, he observed that 433 meteors appeared in the field of view with a diameter of less than 1° near Arcturus. Peter Genese commented that this explosion was similar to “typical passing through the dust tail of a comet”.
Alpha Bootids usually starts on April 14th, with its peaks on 27th and 28th and ends on May 12th. Its meteor speed is slow, about 20.9 kilometers per second, which may be related to 73P / Schwassmann-Wachmann 3, but this is only theoretical speculation.
June Bootids, also known as the ι Draconid, is related to 7P/Pons–Winnecke. It was first discovered by William F. Denning on May 27th, 1916.
This meteor shower, has a low speed, with no observed data before 1916, because the Earth had not crossed the dust tail of this comet before. However, until the orbit of Pons–Winnecke was disturbed by Jupiter, which caused its orbit with the Earth to be close to 0.03AU, the June Bootids was observed for the first time.
It is predicted that in the next 50 years, June Bootids will not have a particularly significant outbreak. Under normal circumstances, only one or two slow and dim meteors can be seen every hour. The average magnitude of June Bootids is 5.0, radiating from the alpha Draco and the Bootes-Draco. This meteor shower lasted from June 27th to July 5th, with the maximum period on June 28th. June Bootids belongs to the third kind of meteor shower which is changeable. The average speed of entry is 18 g/s, and the radiation point is about 7 degrees north of the β Boo.
Mythology of Boötes
There are four different origins about the Greek fairy tales of Bootes, but most of them are related to Arcas, the son of Zeus and Callisto.
- Bootes is Arcas, the son of Zeus and Callisto. One day, Zeus had dinner with Lycaon, the father of callisto. Lycaon chopped Arcas into meat paste in order to test Zeus’s ability. (someone also said it was done by Lycaon’s son). Zeus was furious, killed Lycaon’s son and turned Lycaon into Lupus. Then, Zeus pick up the leftover meat of Arcas and reorganize it, and give it to Maia for care.
- Bootes is Lcarius, the apprentice of Bacchus (the god of wine). Once Lcarius tried the new wine to the shepherd. The shepherd was drunk and thought Lcarius had poisoned the wine, so he killed Lcarius in confusion. The dog of Lcarius escaped and told Erigone, daughter of Lcarius, that Eragone had hanged herself in grief, and the dog died of grief too. Zeus turned Lcarius into the Bootes, turned Eragone into Virgo, and the dog into Canis Major.
- Zeus coveted Callisto’s beauty and abused her. Later, Callisto gave birth to his son Arcas. Queen Hera wanted to punish Callisto for hooking up with her husband, so she turned her into a black bear. For fifteen years, Callisto lived in seclusion in the forest. One day, she met her son Arcas again, but Arcas didn’t know that the black bear in front of her was his mother, so Arcas was ready to raise his spear to defend himself. During the crackle, Zeus swept them to heaven in a whirlwind, and Callisto became Ursa Major, while Arcas became Bootes.
- Zeus and his wife Hera used magic to turn the beautiful fairy Callisto and her child Arcas into Ursa Major and Ursa Minor. Being arrogant and jealous by nature, Hera was unsatisfied, and asked Poseidon to send a hunter with two hounds to chase the two bears in the sky, never allowing them to rest under the horizon. This hunter is Bootes.