The Canes Venatici Constellation

Posted on Friday, 15 December, 2017 by Zheluo Cai

The Canes Venatici Constellation.

Canes Venatici is one of the 88 official modern constellations. It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for “hunting dogs,” and the constellation depicted in illustrations as representing the dogs of Boötes the Herdsman, a neighbouring constellation. Ursa Major borders Canes Venatici to the north and west, Coma Berenices to its south, and Boötes to its east. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 12h 06.2m and 14h 07.3m, while the declination coordinates are between +27.84° and +52.36°. The best viewing month is May. Covering 465 square degrees, it ranks 38th of the 88 constellations in size.

Canes Venatici contains no bright stars, Alpha and Beta Canum Venaticorum being only of 3rd and 4th magnitude respectively. Flamsteed catalogued 25 stars in the constellation, labelling them 1 to 25 Canum Venaticorum. However one turned out to be in Ursa Major, 13 was in Coma Berenices, and 22 did not exist. Alpha Canum Venaticorum, also known as Cor Caroli (“heart of Charles”), is the constellation’s brightest star, named by Sir Charles Scarborough in memory of King Charles I, the deposed king of Britain. Legend has it that α CVn was brighter than usual during the Restoration, as Charles II returned to England to take the throne. Cor Caroli is a wide double star, with a primary of magnitude 2.9 and a secondary of magnitude 5.6; the primary is 110 light-years from Earth and also has an unusually strong variable magnetic field. Beta Canum Venaticorum, or Chara, is a yellow-hued main sequence star of magnitude 4.2, 27 light-years from Earth. Its common name comes from the word for “joy.” Y Canum Venaticorum (La Superba) is a semiregular variable star that varies between magnitudes 5.0 and 6.5 over a period of around 158 days. It is a carbon star and is deep red.

The Giant Void, a huge void, a part of the universe containing very few galaxies, is within the vicinity of this constellation. It may be possibly the most massive void ever discovered, slightly larger than the Eridanus Supervoid and 1,200 times the volume of expected typical voids identified in 1988 in a deep-sky survey.

Canes Venatici contains five Messier objects, including four galaxies. One of the more significant galaxies in Canes Venatici is the Whirlpool Galaxy (M51, NGC 5194) and NGC 5195, a small barred spiral galaxy. It was the first galaxy recognised as having a spiral structure, being first observed by Lord Rosse in 1845. It is a face-on spiral galaxy 37 million light-years from Earth. Widely considered to be one of the most beautiful galaxies visible, M51 has many star-forming regions and nebulae in its arms, colouring them pink and blue in contrast to the older yellow core. M51 has a smaller companion, NGC 5195, that has very few star-forming regions and thus appears yellow.

Other notable spiral galaxies are the Sunflower Galaxy (M63, NGC 5055), M94 (NGC 4736), and M106 (NGC 4258). M63, the Sunflower Galaxy, was named for its appearance. It is a spiral galaxy with an integrated magnitude of 9.0. M94 is a small face-on spiral galaxy with an approximate magnitude of 8.0, about 15 million light-years from Earth. NGC 4631 is a barred spiral galaxy, which is one of the most massive and brightest edge-on galaxies in the sky. M3 (NGC 5272) is a globular cluster 32,000 light-years from Earth. It is 18′ in diameter, and at magnitude 6.3. M94, also classified as NGC 4736, is a face-on spiral galaxy 15 million light-years from Earth. It has very tight spiral arms and a bright core. The outskirts of the galaxy are incredibly luminous in the ultraviolet because of a ring of new stars surrounding the core, 7,000 light-years in diameter. Though astronomers are not sure what has caused this ring of new stars, some hypothesise that it is from shock waves caused by a bar that is thus far invisible. The NASA/ESA Hubble Space Telescope has peered deep into NGC 4631, better known as the Whale Galaxy. Here, a profusion of star birth lights up the galactic centre, revealing bands of dark material between us and the starburst. The galaxy’s activity tapers off in its outer regions where there are fewer stars and less dust, punctuated by pockets of star formation. The Whale Galaxy is about 30 million light-years away from us and is a spiral galaxy much like the Milky Way.