Canes Venatici

Canes Venatici /ˈkeɪniːz vɪˈnætɪsaɪ/ 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 is often depicted in illustrations as representing the dogs of Boötes the Herdsman, a neighboring constellation.

Canes Venatici

Constellation
List of stars in Canes Venatici
Abbreviation	CVn
Genitive	Canum Venaticorum
Pronunciation	/ˈkeɪniːz vɪˈnætɪsaɪ/ KAN-es veh-NAT-ih-see,[1] genitive /ˈkeɪnəm vɪnætɪˈkɒrəm/
Symbolism	the Hunting Dogs
Right ascension	12^h 06.2^m to 14^h 07.3^m
Declination	+27.84° to +52.36°[2]
Area	465 sq. deg. (38th)
Main stars	2
Bayer/Flamsteed stars	21
Stars with planets	4
Stars brighter than 3.00^m	1
Stars within 10.00 pc (32.62 ly)	2
Brightest star	Cor Caroli (Asterion) (α CVn) (2.90^m)
Messier objects	5
Meteor showers	Canes Venaticids
Bordering constellations	Ursa Major Boötes Coma Berenices
Visible at latitudes between +90° and −40°. Best visible at 21:00 (9 p.m.) during the month of May.

Cor Caroli is the constellation's brightest star, with an apparent magnitude of 2.9. La Superba (Y CVn) is one of the reddest naked-eye stars and one of the brightest carbon stars. The Whirlpool Galaxy is a spiral galaxy tilted face-on to observers on Earth, and was the first galaxy whose spiral nature was discerned. In addition, TON 618 has one of the most massive black holes with the mass of 66 billion solar masses.

History

Canes Venatici as depicted in Hevelius's star atlas. Note that, per the conventions of the time, the image is mirrored.

Canes Venatici can be seen in the orientation it appears to the eyes in this 1825 star chart from Urania's Mirror.

The stars of Canes Venatici are not bright. In classical times, they were listed by Ptolemy as unfigured stars below the constellation Ursa Major in his star catalogue.

In medieval times, the identification of these stars with the dogs of Boötes arose through a mistranslation: some of Boötes's stars were traditionally described as representing the club (Greek: κολλοροβος, kollorobos) of Boötes. When the Greek astronomer Ptolemy's Almagest was translated from Greek to Arabic, the translator Hunayn ibn Ishaq did not know the Greek word and rendered it as a similar-sounding compound Arabic word for a kind of weapon, writing العصا ذات الكُلاب‎ al-'aşā dhāt al-kullāb, which means 'the staff having a hook'.

When the Arabic text was later translated into Latin, the translator, Gerard of Cremona, mistook كُلاب‎ kullāb ('hook') for كِلاب‎ kilāb ('dogs'). Both written words look the same in Arabic text without diacritics, leading Gerard to write it as Hastile habens canes ('spearshaft-having dogs').[3] In 1533, the German astronomer Peter Apian depicted Boötes as having two dogs with him.[4]

These spurious dogs floated about the astronomical literature until Hevelius decided to make them a separate constellation in 1687.[5] Hevelius chose the name Asterion[lower-alpha 1] for the northern dog and Chara[lower-alpha 2] for the southern dog, as Canes Venatici, 'the hunting dogs', in his star atlas.[7]

In his star catalogue, the Czech astronomer Antonín Bečvář assigned the names Asterion to β CVn and Chara to α CVn.[8]

Although the International Astronomical Union dropped several constellations in 1930 that were medieval and Renaissance innovations, Canes Venatici survived to become one of the 88 IAU designated constellations.[9]

Neighbors and borders

Canes Venatici is bordered by Ursa Major to the north and west, Coma Berenices to the south, and Boötes to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CVn".[10] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930,[9] are defined by a polygon of 14 sides.

In the equatorial coordinate system, the right ascension coordinates of these borders lie between 12^h 06.2^m and 14^h 07.3^m , while the declination coordinates are between +27.84° and +52.36°.[2] Covering 465 square degrees, it ranks 38th of the 88 constellations in size.

Prominent stars and deep-sky objects

The constellation Canes Venatici as it is seen by the naked eye in twilight

Stars

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 (CVn); however, 1 CVn turned out to be in Ursa Major, 13 CVn was in Coma Berenices, and 22 CVn did not exist.[11]

• 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.[12][lower-alpha 3][lower-alpha 4] Legend has it that α CVn was brighter than usual during the Restoration, as Charles II returned to England to take the throne.[16] 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. The primary also has an unusually strong variable magnetic field.[12]
• 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.[12]
• 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 in color.[12]
• AM Canum Venaticorum, a very blue star of magnitude 14, is the prototype of a special class of cataclysmic variable stars, in which the companion star is a white dwarf, rather than a main sequence star.
• RS Canum Venaticorum is the prototype of a special class of binary stars[17] of chromospherically active and optically variable components.
• R Canum Venaticorum is a Mira variable that ranges between magnitudes 6.5 and 12.9 over a period of approximately 329 days.

Supervoid

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

Deep-sky objects

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 that is seen face-on. This was the first galaxy recognised as having a spiral structure, this structure being first observed by Lord Rosse in 1845.[12] 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, coloring them pink and blue in contrast to the older yellow core. M 51 has a smaller companion, NGC 5195, that has very few star-forming regions and thus appears yellow. It is passing behind M 51 and may be the cause of the larger galaxy's prodigious star formation.[18]

• 
  Messier 51, the Whirlpool Galaxy, photographed by the Hubble Space Telescope.
• 
  NGC 4248 is located about 24 million light-years away.[19]
• 
  NGC 4242 is a dim galaxy in Canes Venatici.[20]
• 
  NGC 4631 photographed by the Hubble Space Telescope.
• 
  NGC 4707 is a spiral galaxy roughly 22 million light-years from Earth.[21]

Other notable spiral galaxies in Canes Venatici are the Sunflower Galaxy (M63, NGC 5055), M94 (NGC 4736), and M106 (NGC 4258).

• M63, the Sunflower Galaxy, was named for its appearance in large amateur telescopes. It is a spiral galaxy with an integrated magnitude of 9.0.
• M94 (NGC 4736) is a small face-on spiral galaxy with approximate magnitude 8.0, about 15 million light-years from Earth.[12]
• NGC 4631 is a barred spiral galaxy, which is one of the largest and brightest edge-on galaxies in the sky.[22]
• M3 (NGC 5272) is a globular cluster 32,000 light-years from Earth. It is 18′ in diameter, and at magnitude 6.3 is bright enough to be seen with binoculars. It can even be seen with the naked eye under particularly dark skies.[12]
• M94, also cataloged 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 hypothesize that it is from shock waves caused by a bar that is thus far invisible.[18]

TON 618 is a hyperluminous quasar and blazar in this constellation, near its border with the neighboring Coma Berenices. It possesses a black hole with a mass 66 billion times that of our Sun, making it one of the most massive black holes ever measured.

Footnotes

1. Hevelius' name for the northern dog, Asterion, is from the Greek αστέριον, meaning the 'little star',[6] the diminutive of αστηρ 'the star' or 'starry'. (Allen 1963, p. 115)
2. Hevelius' name for the southern dog, Chara, is from the Greek χαρά, meaning 'joy'.(Allen 1963, p. 115)
3. According to Warner,[13] it was originally named Cor Caroli Regis Martyris ('The Heart of King Charles the Martyr') for Charles I.
4. Allen states that Edmund Halley formally designated the star "Cor Caroli" in 1725, while Burnham believes there is not conclusive evidence, as "the attribution of the name to Halley appears in a report published by J. E. Bode at Berlin in 1801, but seems to have no other verification".[14][15]

References

1. "Constellation Pronunciation Guide". Space.com. 13 December 2006. Archived from the original on 2020-10-03. Retrieved 2020-10-03.
2. Canes Venatici, constellation boundary (Report). The Constellations. International Astronomical Union. Archived from the original on 2014-02-16. Retrieved 15 February 2014.
3. Allen 1963, p. 105; Kunitzsch 1959, pp. 123–124; Kunitzsch 1974, pp. 227–228 harvnb error: no target: CITEREFKunitzsch1974 (help); Kunitzsch 1990, pp. 48–49
4. Apianus 1533; Allen 1963, p. 157
5. Ridpath, Ian. "Canes Venatici". Star Tales. Archived from the original on 2020-10-04. Retrieved 9 June 2012.; Ridpath 2001, pp. 96–97 harvnb error: no target: CITEREFRidpath2001 (help)
6. Kunitzsch, P.; Smart, T. (2006). A Dictionary of Modern Star Names: A short guide to 254 star names and their derivations (2nd revised ed.). Sky Publishing. p. 22. ISBN 1-931559-44-9.
7. Ridpath 2001, pp. 96–97 harvnb error: no target: CITEREFRidpath2001 (help); Hevelius 1690
8. Bečvář 1951
9. Delporte, Eugène (1930). Délimitation scientifique des constellations. International Astronomical Union.
10. Russell, Henry Norris (1922). "The New International Symbols for the Constellations". Popular Astronomy. 30: 469–471. Bibcode:1922PA.....30..469R.
11. Wagman, Morton (October 2003). Lost Stars: Lost, missing and troublesome stars from the catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and sundry others. Blacksburg, VA: McDonald and Woodward. p. 366. ISBN 978-0-939923-78-6.
12. Ridpath 2001, pp. 96–97 harvnb error: no target: CITEREFRidpath2001 (help)
13. Warner, Deborah J. The Sky Explored: Celestial cartography 1500–1800.
14. Burnham, Robert, Jr. (1978). Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System. 1. Dover Publications.
15. Burnham 1978, p. 359, quoted in Barentine (2016, p. 352).
16. Barentine, John C. (2016). The Lost Constellations: A History of Obsolete, Extinct, or Forgotten Star Lore. Popular Astronomy. Switzerland: Springer International. p. 352. doi:10.1007/978-3-319-22795-5. ISBN 978-3-319-22795-5. according to Allen (1899), the name Cor Caroli was suggested by 'the court physician, Sir Charles Scarborough, who said that it had shone with special brilliancy on the eve of the king's return to London on the 29th of May, 1660.'
17. "V* RS CVn". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 9 June 2012.
18. Wilkins, Jamie; Dunn, Robert (August 2006). 300 Astronomical Objects: A visual reference to the universe. Firefly Books. ISBN 9781554071753.
19. "A cosmic atlas". Hubble Space Telescope. European Space Agency. 24 July 2017. Archived from the original on 2017-07-31. Retrieved 24 July 2017.
20. "Dim and diffuse". Hubble Space Telescope. European Space Agency. 17 July 2017. Archived from the original on 2017-07-19. Retrieved 17 July 2017.
21. "Astro-pointillism". Hubble Space Telescope. European Space Agency. 19 December 2016. Archived from the original on 2016-12-20. Retrieved 19 December 2016.
22. O'Meara, Stephen James (January 2002). The Caldwell Objects. Sky Publishing Corporation. p. 126. ISBN 0-933346-97-2.

Bibliography

• Allen, Richard Hinckley (1963) [1899]. Star Names: Their lore and meaning. New York, NY: Dover Publications. ISBN 0-486-21079-0.
• Apianus, Petrus (1533). Horoscopion generale (in Latin).
• Bečvář, Antonín (1951). Atlas Coeli (II – Catalogue 1950.0 ed.). Czechoslovak Astronomical Society.
• Hevelius, Johannes (1690). Firmamentum Sobiescianum (in Latin).
• Kunitzsch, P. (1959). Arabische Sternnamen in Europa (in German). Otto Harassowitz.
• Ptolemäus, Claudius (1974). Der Almagest: Die Syntaxis Mathematica des Claudius Ptolemäus in arabisch-lateinischer Ūberlieferung. Translated by Kunitzsch, P. Otto Harassowitz.
• Kunitzsch, P. (1990). Der Sternkatalog des Almagest die arabisch-mittelalterliche Tradition (in German). II Die lateinische Ūbersetzung Gerhards von Cremona. Otto Harassowitz.

External links

• Photos of Canes Venatici and the star clusters and galaxies found within it on AllTheSky.com
• Clickable map of Canes Venatici
• Photographic catalogue of deep sky objects in Canes Venatici (PDF)