Canopus (//), also designated α Carinae (Latinised to Alpha Carinae, abbreviated Alpha Car, α Car), is the brightest star in the southern constellation of Carina, and the second-brightest star in the night sky, after Sirius. Canopus' visual magnitude is −0.74, and it has an absolute magnitude of −5.71.
An image of Canopus by Expedition 6
Epoch J2000 Equinox J2000
|Right ascension||06h 23m 57.10988s|
|Declination||−52° 41′ 44.3810″|
|Apparent magnitude (V)||−0.74|
|Spectral type||A9 II|
|U−B color index||+0.10|
|B−V color index||+0.15|
|Radial velocity (Rv)||20.3 km/s|
|Proper motion (μ)|| RA: 19.93 mas/yr |
Dec.: 23.24 mas/yr
|Parallax (π)||10.55 ± 0.56 mas|
|Distance||310 ± 20 ly |
(95 ± 5 pc)
|Absolute magnitude (MV)||–5.71|
|Mass||8.0 ± 0.3 M☉|
|Radius||71 ± 4 R☉|
|Surface gravity (log g)||1.64 ± 0.05 cgs|
|Metallicity [Fe/H]||–0.07 dex|
|Rotational velocity (v sin i)||8.0 km/s|
Canopus is a bright giant of spectral type A9, so it is essentially white when seen with the naked eye. It is located in the far southern sky, at a year 2000 declination of −52° 42′ and a right ascension of 06h 24.0m.
In Indian Vedic literature, the star Canopus is associated with the sage Agastya, one of the ancient rishis (the others are associated with the stars of the Big Dipper). Agastya, the star, is said to be the 'cleanser of waters' and its rising coincides with the calming of the waters of the Indian Ocean. It is considered the son of Pulasthya, son of Brahma.
Canopus was not visible to the mainland ancient Greeks and Romans; it was, however, visible to the ancient Egyptians. Hence Aratus did not write of the star as it remained below the horizon, while Eratosthenes and Ptolemy—observing from Alexandria—did, calling it Kanōbos.
The Bedouin people of the Negev and Sinai also knew Canopus as Suhayl, and used it and Polaris as the two principal stars for navigation at night. Because it disappears below the horizon in those regions, it became associated with a changeable nature, as opposed to always-visible Polaris, which was circumpolar and hence 'steadfast'. It is also referred to by its Arabic name: سهيل (Suhayl, Soheil in Persian), given by Islamic scientists in the 7th century AD.
Called the Old Man of the South Pole (in Chinese: 南极老人; pinyin: Nanji Lǎorén) in Chinese, Canopus appears (albeit misplaced northwards) on the medieval Chinese manuscript the Dunhuang star chart, although it cannot be seen from the Chinese capital of Chang'an. The Chinese astronomer Yi Xing had journeyed south to chart Canopus and other far southern stars in 724 AD. However, it was already mentioned by Sima Qian in the second century BC, drawing on sources from the Warring States period, as the southern counterpart of Sirius.
Bright stars were important to the ancient Polynesians for navigation between the many islands and atolls of the Pacific Ocean. Low on the horizon, they acted as stellar compasses to assist mariners in charting courses to particular destinations. Canopus served as the southern wingtip of a "Great Bird" constellation called Manu, with Sirius as the body and Procyon the northern wingtip, which divided the Polynesian night sky into two hemispheres. The Hawaiian people called Canopus Ke Alii-o-kona-i-ka-lewa, "The chief of the southern expanse"; it was one of the stars used by Hawaii-loa and Ki when they traveled to the Southern Ocean.
The Māori people of New Zealand/Aotearoa had several names for Canopus. Ariki ("High-born"), was known as a solitary star that appeared in the east, prompting people to weep and chant. They also named it Atutahi, Aotahi or Atuatahi, "Stand Alone". Its solitary nature indicates it is a tapu star, as tapu people are often solitary. Its appearance at the beginning of the Maruaroa season foretells the coming winter; light rays to the south indicate a cold wet winter, and to the north foretell a mild winter. Food was offered to the star on its appearance. This name has several mythologies attached to it. One story tells of how Atutahi was left outside the basket representing the Milky Way when Tāne wove it. Another related myth about the star says that Atutahi was the first-born child of Rangi, who refused to enter the Milky Way and so turned it sideways and rose before it. The same name is used for other stars and constellations throughout Polynesia. Kapae-poto, "Short horizon", referred to it rarely setting as seen in New Zealand; Kauanga ("Solitary") was the name for Canopus only when it was the last star visible before sunrise.
The Tswana people of Botswana knew Canopus as Naka. Appearing late in winter skies, it heralded increasing winds and a time when trees lose their leaves. Stock owners knew it was time to put their sheep with rams. In southern Africa, the Sotho, Tswana and Venda people called Canopus Naka or Nanga, “the Horn Star”, while the Zulu and Swazi called it inKhwenkwezi "Brilliant star". It appears in the predawn sky in the third week of May. According to the Venda, the first person to see Canopus would blow a phalaphala horn from the top of a hill, getting a cow for a reward. The Sotho chiefs also awarded a cow, and ordered their medicine men to roll bone dice and read the fortune for the coming year. To the ǀXam-speaking Bushmen of South Africa, Canopus and Sirius signalled the appearance of termites and flying ants. They also believed that stars had the power to cause death and misfortune, and they would pray to Sirius and Canopus in particular to impart good fortune or skill.
The Kalapalo people of Mato Grosso state in Brazil saw Canopus and Procyon as Kofongo "Duck", with Castor and Pollux representing his hands. The asterism's appearance signified the coming of the rainy season and increase in manioc, a food staple fed to guests at feasts.
Canopus traditionally marked the rudder of the ship Argo Navis. English explorer Robert Hues brought it to the attention of European observers in his 1592 work Tractatus de Globis, along with Achernar and α Centauri, noting:
"Now, therefore, there are but three Stars of the first magnitude that I could perceive in all those parts which are never seene here in England. The first of these is that bright Star in the sterne of Argo which they call Canobus. The second is in the end of Eridanus. The third is in the right foote of the Centaure."
In the southern hemisphere, Canopus and Sirius are both visible high in the sky simultaneously, and reach the meridian just 21 minutes apart. Brighter than first magnitude, Canopus can be seen by naked eye already in the early twilight. Most visible in the Southern Hemisphere summer, Canopus culminates at midnight on December 27, and at 9 PM on February 11.
It is a circumpolar star when seen from points with latitude south of 37°18' S; for example, Victoria and Tasmania, Australia; Auckland and south of it, New Zealand; Bahía Blanca, Argentina; and Valdivia, Chile and south of these cities in South America. Since Canopus is so far south in the sky, it never rises in mid- to far-northern latitudes; in theory the northern limit of visibility is latitude 37°18' north. This is just south of Athens, Richmond (USA), and San Francisco, and very close to Seville and Agrigento. It is almost exactly the latitude of Lick Observatory on Mt. Hamilton, California, from which it is readily visible because of the effects of elevation and atmospheric refraction, which add another degree to its apparent altitude. Under ideal conditions it has been spotted as far north as latitude 37°31' from the Pacific coast. Another northernmost record of visibility came from Mount Nemrut in Turkey, latitude 37°59'. It is more easily visible in places such as the Gulf Coast and Florida, and the island of Crete (Greece) where the best season for viewing it around 9 p.m. is during late January and early February.
Canopus has a B–V color index of +0.15 where 0 is a blue-white, indicating it is essentially white, although has been described as yellow-white. Its spectral type has been recorded as F0 and more recently A9. It has less yellow than Altair or Procyon, whose color indices have been measured at 0.22 and 0.42, respectively. It may be that some observers have perceived it as yellow-tinged because it is low in the sky and hence subject to atmospheric effects. Patrick Moore argued that it never appeared anything but white to him.
Before the launch of the Hipparcos satellite telescope, distance estimates for Canopus varied widely, from 96 light-years to 1200 light-years. Had the latter distance been correct, Canopus would have been one of the most luminous stars in the Milky Way galaxy. Hipparcos established Canopus as being 310 light-years (96 parsecs) from the Solar System; this is based on its 2007 parallax measurement of 10.43 ± 0.53 mas.
Canopus has an MK spectral type of A9 II, although it has also been classified as F0Ib (Ib referring to "less luminous supergiant") on account of its high luminosity, or F0II. The effective temperature of Canopus has been measured to be 6,998 K. Very long baseline interferometry has been used to calculate its angular diameter at 6.9 mas. Combined with distance calculated by Hipparcos, this gives it a radius of 71 times that of the Sun. If it were at the centre of the Solar System, it would extend 90% of the way to the orbit of Mercury. It is over ten thousand times more luminous than the Sun.
Canopus is a source of X-rays, which are probably produced by its corona, magnetically heated to several million K. The temperature has likely been stimulated by fast rotation combined with strong convection percolating through the star's outer layers.
No star closer than Canopus is more luminous than it, and it has been the brightest star in Earth's night sky during three epochs over the past four million years. Other stars appear brighter only during relatively temporary periods, during which they are passing the Solar System much closer than Canopus. About 90,000 years ago, Sirius moved close enough that it became brighter than Canopus, and that will remain so for another 210,000 years. But in 480,000 years, Canopus will once again be the brightest, and will remain so for a period of about 510,000 years.[dubious ]
Canopus was previously proposed to be a member of the Scorpius-Centaurus Association, however it is not located near the subgroups of that association, and has not been included as a Sco-Cen member in kinematic studies that used Hipparcos astrometric data. At present, Canopus is not thought to be a member of any nearby young stellar groups. Its position in the H-R diagram indicates that it is a massive giant star currently in the core-helium burning phase.
In 2014, astronomer Eric Mamajek reported that an extremely magnetically active M dwarf (having strong coronal X-ray emission), 1.16 degrees south of Canopus, appears to share common proper motion with Canopus. The projected separation of the M dwarf 2MASS J06234738-5351131 ("Canopus B") is approximately 1.9 parsecs, however, despite this large separation, it is still within the estimated tidal radius (2.9 parsecs) for the massive star Canopus.
Etymology and cultural significanceEdit
α Carinae (Latinised to Alpha Carinae) is the star's Bayer designation. It is also listed in the Bright Star Catalogue as HR 2326, the Henry Draper Catalogue as HD 45348, and the Hipparcos catalogue as HIP 30438. Flamsteed did not number this southern star, but Gould gave it the number 7 (7 G. Carinae) in his Uranometria Argentina.
The name Canopus is a Latinisation of the Ancient Greek name Κάνωβος/Kanôbos, recorded in Claudius Ptolemy's Almagest (c150 AD). Eratosthenes used the same spelling. Hipparchos wrote it as Κάνωπος. John Flamsteed wrote Canobus, as did Edmond Halley in his 1679 Catalogus Stellarum Australium. The name has two common derivations, both listed in Richard Hinckley Allen's seminal Star Names: Their Lore and Meaning; and one which is less common. All are matters of conjecture:
- One from the legend of the Trojan War, where the constellation Carina was once part of the now-obsolete constellation of Argo Navis, which represented the ship used by Jason and the Argonauts. The brightest star in the constellation was given the name of a ship's pilot from another Greek legend: Canopus, pilot of Menelaus' ship on his quest to retrieve Helen of Troy after she was taken by Paris.
- A second from the Egyptian Coptic Kahi Nub ("Golden Earth"), which refers how Canopus would have appeared near the horizon in ancient Egypt, reddened by atmospheric extinction from that position. A ruined ancient Egyptian port named Canopus lies near the mouth of the Nile, site of the Battle of the Nile.
- A third is its possible origin from the Semitic root G(C)-N-B (Gimmel-Nun-Beth), from which the Arabic word for south, janūb ( جنوب ), is derived. The southeastern wall of the Kaaba in Mecca is aligned with the rising point of Canopus, and is also named Janūb.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Canopus for this star. It is now so entered in the IAU Catalog of Star Names.
It is also personified as the Shou star.
In Japan, Canopus is known as Mera-boshi and Roujin-sei (the old man star).
In traditional Tibetan astronomy and astrology, Canopus is named Karma Rishi སྐར་མ་རི་ཥི།
Canopus was identified as the moiety ancestor Waa "Crow" to some Koori people in southeastern Australia. The Boorong people of northwestern Victoria recalled that War (Canopus) was the brother of Warepil (Sirius), and that he brought fire from the heavens and introduced it to mankind. His wife was Collowgullouric War (Eta Carinae). The Pirt-Kopan-noot people of western Victoria told of Waa "Crow" falling in love with a queen, Gneeanggar "Wedge-tailed Eagle" (Sirius) and her six attendants (the Pleiades). His advances spurned, he hears that the women are foraging for grubs and so transforms himself into a grub. When the women dig him out, he changes into a giant and carries her off.
The Kulin people knew Canopus as Lo-an-tuka. Objects in the sky were also associated with states of being for some tribes; the Wailwun of northern New South Wales knew Canopus as Wumba "deaf", alongside Mars as Gumba "fat" and Venus as Ngindigindoer "you are laughing". Tasmanian aboriginal lore held that Canopus was Dromerdene, the brother of Moinee; the two fought and fell out of the sky, with Dromerdene falling into Louisa Bay in southwest Tasmania.
Canopus was known to the ancient Mesopotamians and given the name NUN-ki and represented the city of Eridu in the Three Stars Each Babylonian star catalogues and later MUL.APIN around 1100 BC. Today, the star Sigma Sagittarii is known by the common name Nunki.
An occasional name seen in English is Soheil, or the feminine Soheila; in Turkish is Süheyl, or the feminine Süheyla, from the Arabic name for several bright stars, سهيل suhayl, and Canopus was known as Suhel in medieval times. Alternative spellings include Suhail, Souhail, Suhilon, Suheyl, Sohayl, Suhayil, Shoel, Sohil, Soheil, Sahil, Suhayeel, Sohayil, Sihel, and Sihil. An alternative name was Wazn "weight" or Haḍar "ground", possibly related to its low position near the horizon. Hence comes its name in the Alphonsine Tables, Suhel ponderosus, a Latinization of Al Suhayl al Wazn. Its Greek name was revived during the Renaissance.
The people of the Society Islands had two names for Canopus, as did the Tuamotu people. The Society Islanders called Canopus Taurua-e-tupu-tai-nanu, "Festivity-whence-comes-the-flux-of-the-sea", and Taurua-nui-o-te-hiti-apatoa "Great-festivity-of-the-border-of-the-south", and the Tuamotu people called the star Te Tau-rari and Marere-te-tavahi, the latter said to be the true name for the former, "He-who-stands-alone".
Among New Zealand Maori Canopus is a circumpolar star called Atutahi (variants include Autahi and Aotahi). Atutahi was considered so sacred that he stood alone outside the Milky Way, it was an important weather predictor and indicated when soils were ready for planting. Te Taki o Atutahi referred to the stars role in leading Te Punga (the anchor) i.e. the Southern Cross.
In modern times, Canopus serves another navigational use. Canopus's brightness and location well off the ecliptic make it popular for space navigation. Many spacecraft carry a special camera known as a "Canopus Star Tracker" plus a Sun sensor for attitude determination.
- van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
- Ducati, J. R. (2002). "Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D. Vizier catalog entry
- Gray, R. O.; Garrison, R. F. (1989). "The early F-type stars – Refined classification, confrontation with Stromgren photometry, and the effects of rotation". Astrophysical Journal Supplement Series. 69: 301. Bibcode:1989ApJS...69..301G. doi:10.1086/191315.
- Lopez-Cruz, O.; Garrison, R. F. (1993). "A Spectroscopic Study of High Galactic Latitude F Supergiant Stars". Luminous High-Latitude Stars. the International Workshop on Luminous High-Latitude Stars. 45: 59. Bibcode:1993ASPC...45...59L.
- Gontcharov, G. A. (2007). "Pullkovo Compilation of Radial Velocities for 39495 Hipparcos stars in a common system". Astronomy Letters. 32 (1): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. Vizier catalog entry
- Smiljanic, R.; et al. (April 2006). "CNO in evolved intermediate mass stars". Astronomy and Astrophysics. 449 (2): 655–671. arXiv:astro-ph/0511329. Bibcode:2006A&A...449..655S. doi:10.1051/0004-6361:20054377.
- Cruzalèbes, P.; Jorissen, A.; Rabbia, Y.; Sacuto, S.; Chiavassa, A.; Pasquato, E.; Plez, B.; Eriksson, K.; Spang, A.; Chesneau, O. (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434: 437. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037.
- Frawley, David (1993). Gods, Sages and Kings: Vedic Secrets of Ancient Civilization. New Delhi, India: Motilal Banarsidass.
- Schaaf, p. 107.
- Ridpath, Ian. "Carina". Star Tales. self-published. Retrieved 10 December 2015.
- Maryboy, Nancy D. (2004). A Guide to Navajo Astronomy. Indigenous Education Institute : Bluff, Utah.
- Antonio Rumeu de Armas (1975). La conquista de Tenerife, 1494–1496. Aula de Cultura de Tenerife.
- Bailey, Clinton (1974). "Bedouin Star-Lore in Sinai and the Negev". Bulletin of the School of Oriental and African Studies, University of London (abstract). 37 (3): 580–96. doi:10.1017/S0041977X00127491. JSTOR 613801.
- Bonnet-Bidaud, Jean-Marc; Praderie, Françoise; Whitfield, Susan (2009). "The Dunhuang Sky: A Comprehensive Study of the Oldest Known Star Atlas". The International Dunhuang Project: The Silk Road Online. 12: 39. arXiv:0906.3034. Bibcode:2009JAHH...12...39B.
- Needham, Joseph (1959). Science and Civilisation in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Cambridge, United Kingdom: Cambridge University Press. p. 274. ISBN 0521058015.
- Holberg, J.B. (2007). Sirius: Brightest Diamond in the Night Sky. Chichester, UK: Praxis Publishing. pp. 25–26. ISBN 0-387-48941-X.
- Makemson 1941, p. 198.
- Makemson 1941, p. 201.
- p. 419, Mythology: Myths, Legends and Fantasies, Janet Parker, Alice Mills, Julie Stanton, Durban, Struik Publishers, 2007.
- Best, Elsdon (1922). Astronomical Knowledge of the Maori: Genuine and Empirical. Wellington, New Zealand: Dominion Museum. pp. 34–35.
- Makemson 1941, pp. 200–202.
- Makemson 1941, p. 217.
- Makemson 1941, p. 218.
- Clegg, Andrew (1986). "Some Aspects of Tswana Cosmology". Botswana Notes and Records. 18: 33–37. JSTOR 40979758.
- Snedegar, K.V. (1995). "Stars and seasons in Southern Africa". Vistas in Astronomy. 39 (4): 529–38. doi:10.1016/0083-6656(95)00008-9.
- Hollman, J. C. (2007). ""The Sky's Things", |xam Bushman 'Astrological Mythology' as recorded in the Bleek and Lloyd Manuscripts". African Sky. 11: 8. Bibcode:2007AfrSk..11....8H.
- Basso, Ellen B. (1987). In Favor of Deceit: A Study of Tricksters in an Amazonian Society. Tucson, Arizona: University of Arizona Press. p. 360. ISBN 0816510229.
- Knobel, E. B. (1917). "On Frederick de Houtman's Catalogue of Southern Stars, and the Origin of the Southern Constellations". Monthly Notices of the Royal Astronomical Society. 77 (5): 414–32 . Bibcode:1917MNRAS..77..414K. doi:10.1093/mnras/77.5.414.
- Knobel, p. 416.
- Motz, Lloyd; Nathanson, Carol (1991). The Constellations: An Enthusiast's Guide to the Night Sky. London, United Kingdom: Aurum Press. pp. 376–77. ISBN 1-85410-088-2.
- Schaaf, p. 257.
- D. Gieringer, "Exploring the Tropic of Canopus," Astronomy, December 1985, p.24.
- Tezel, Tunç (8 Oct 2013). "Zodiacal Light and Nemrut Heritage". The World At Night (TWAN). Retrieved 17 March 2014.
- Schaaf, pp. 112–13.
- Moore, Patrick (2000). Exploring the night sky with binoculars (4th ed.). Cambridge University Press. p. 69. ISBN 9780521793902.
- Domiciano De Souza, A.; Bendjoya, P.; Vakili, F.; Millour, F.; Petrov, R. G. (2008). "Diameter and photospheric structures of Canopus from AMBER/VLTI interferometry". Astronomy and Astrophysics. 489 (2): L5–L8. Bibcode:2008A&A...489L...5D. doi:10.1051/0004-6361:200810450.
- Kaler, Jim (26 June 2009). "Canopus". Stars. University of Illinois. Retrieved 8 July 2012.
- Ness, J.-U.; Güdel, M.; Schmitt, J. H. M. M.; Audard, M.; Telleschi, A. (2004). "On the sizes of stellar X-ray coronae". Astronomy and Astrophysics. 427 (2): 667. arXiv:astro-ph/0407231. Bibcode:2004A&A...427..667N. doi:10.1051/0004-6361:20040504.
- Sky and Telescope, April 1998 (p60), based on computations from HIPPARCOS data.
- de Zeeuw, P.T.; Hoogerwerf, R.; de Bruijne, J.H.J; Brown, A.G.A; Blaauw, A. (1999). "A HIPPARCOS Census of the Nearby OB Associations". The Astronomical Journal. 117: 354–399. arXiv:astro-ph/9809227. Bibcode:1999AJ....117..354D. doi:10.1086/300682.
- Mamajek, Eric (11 August 2014). "Canopus B: A Candidate Common Proper Motion Companion to the Second Brightest Star". Figshare. Retrieved 13 August 2014.
- Flamsteed, John (1729). Atlas coelestis. London, United Kingdom. pp. Constellation Map of Southern Hemisphere.
- Halley, Edmond (1679). Catalogus stellarum australium; sive, Supplementum catalogi Tychenici, exhibens longitudines et latitudines stellarum fixarum, quae, prope polum Antarcticum sitae, in horizonte Uraniburgico Tychoni inconspicuae fuere, accurato calculo ex distantiis supputatas, & ad annum 1677 completum correctas...Accedit appendicula de rebus quibusdam astronomicis. London: T. James. p. 30.
- Allen, Richard Hinckley (1963) . Star Names: Their Lore and Meaning (Revised ed.). New York: Dover Publications. pp. 67–72. ISBN 0-486-21079-0.
- Islamic Awareness. "Astronomical Orientation Of Ka`bah".
- "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
- "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
- "IAU Catalog of Star Names". Retrieved 28 July 2016.
- Martianus Capella 7.838, Hazzard; Fitzgerald (1991). "The Regulation of the Ptolemeia". Journal of the Royal Astronomical Society of Canada. 85: 6–23. Bibcode:1991JRASC..85....6H.; Hazzard. 2000. Imagination of a Monarchy: Studies in Ptolemaic Propaganda, 34–36.
- Takao Ibaraki (1996-07-14). "Stellar Iconology and Astronomical Folklore in Japan". International Planetarium Society (IPS) Conferences 1996. Osaka: International Planetarium Society. Archived from the original on 2012-03-26. Retrieved 2012-02-25.
- Mudrooroo (1994). Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day. London: HarperCollins. p. 27. ISBN 1-85538-306-3.
- Hamacher, Duane W.; Frew, David J. (2010). "An Aboriginal Australian Record of the Great Eruption of Eta Carinae". Journal of Astronomical History & Heritage. 13 (3): 220–34. arXiv:1010.4610. Bibcode:2010JAHH...13..220H.
- Mudroodoo, p. 55.
- Johnson, Diane (1998). Night skies of aboriginal Australia: a noctuary. Darlington, New South Wales: University of Sydney. p. 84. ISBN 1-86451-356-X.
- Haynes, Ros D. (2000). Astronomy and the Dreaming: The Astronomy of the Aboriginal Australians. Astronomy Across Cultures: The History of Non-Western Astronomy. Kluwer Academic Publishers. p. 57. doi:10.1007/978-94-011-4179-6_3.
- Rogers, John H. (1998). "Origins of the Ancient Constellations: I. The Mesopotamian Traditions". Journal of the British Astronomical Association. 108 (1): 9–28. Bibcode:1998JBAA..108....9R.
- Allen, Richard Hinckley, Star Names, their lore and meaning, p. 359
- Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, MA: Sky Pub. p. 23. ISBN 978-1-931559-44-7.
- Makemson 1941, p. 259.
- Makemson 1941, p. 229.
- Taylor, Kieron (1 March 1994). "Precession". myweb.tiscali.co.uk. Retrieved 2012-02-25.
- "Astronomy of the Brazilian Flag". FOTW Flags Of The World website.