Corona Australis is a Southern Celestial Hemisphere constellation. It is the southern counterpart of Corona Borealis, the northern crown, and its Latin name means "southern crown." Claudius Ptolemy, a 2nd-century astronomer, listed forty-eight constellations, and it is still one among the eighty-eight contemporary constellations. Corona Australis was related to Sagittarius or Centaurus by the Ancient Greeks, who saw it as a wreath rather than a crown. The pattern has been compared to a turtle, an ostrich nest, a tent, and even a rock hyrax's home in other civilizations.
The oval- or horseshoe-shaped pattern of its brighter stars distinguishes it from its northern cousin, although being fainter. The two brightest stars, Alpha, and Beta Coronae Australis have an apparent magnitude of roughly 4.1. The brightest W Ursae Majoris variable in the southern sky is Epsilon Coronae Australis. Corona Australis, which lies alongside the Milky Way, features one of the Solar System's closest star-forming areas, a dusty dark nebula is known as the Corona Australis Molecular Cloud, which is roughly 430 light years away. It contains stars in the early phases of their careers. Parts of the nebula are illuminated by the variable stars R and TY Coronae Australis, which vary in brightness.
When the International Astronomical Union (IAU) created the eighty-eight contemporary constellations in 1922, the name of the constellation was entered as "Corona Australis." When the IAU's commission on notation approved a list of four-letter abbreviations for the constellations in 1932, the name was changed to "Corona Austrina." (Schlesinger 1932) In 1955, the four-letter abbreviations were abolished. The International Astronomical Union (IAU) now solely uses the term "Corona Australis."
The oval- or horseshoe-shaped pattern of its brighter stars distinguishes it from its northern cousin, although being fainter. The two brightest stars, Alpha, and Beta Coronae Australis have an apparent magnitude of roughly 4.1. The brightest W Ursae Majoris variable in the southern sky is Epsilon Coronae Australis. Corona Australis, which lies alongside the Milky Way, features one of the Solar System's closest star-forming areas, a dusty dark nebula is known as the Corona Australis Molecular Cloud, which is roughly 430 light years away. It contains stars in the early phases of their careers. Parts of the nebula are illuminated by the variable stars R and TY Coronae Australis, which vary in brightness.
When the International Astronomical Union (IAU) created the eighty-eight contemporary constellations in 1922, the name of the constellation was entered as "Corona Australis." When the IAU's commission on notation approved a list of four-letter abbreviations for the constellations in 1932, the name was changed to "Corona Austrina." (Schlesinger 1932) In 1955, the four-letter abbreviations were abolished. The International Astronomical Union (IAU) now solely uses the term "Corona Australis."
Characteristics
Corona Australis is a tiny constellation bounded on the north by Sagittarius, the west by Scorpius, the south by Telescopium, and the southwest by Ara. The International Astronomical Union chose the three-letter abbreviation "CrA" for the constellation in 1922. (Russell 1922) A four-segment polygon defines the official constellation borders, which were established by Belgian astronomer Eugène Delporte in 1930. The right ascension coordinates of these borders are between 17h 58.3m and 19h 19.0m in the equatorial coordinate system, while the declination coordinates are between 36.77° and 45.52°. Corona Australis, with a surface size of 128 square degrees, peaks about midnight on June 30th and ranks 80th in terms of area. Only visible south of 53° north latitude, Corona Australis is too far south to be viewed from the British Isles, although it may be seen from southern Europe (Moore 2005) and the southern United States. (Moore 2000) |
History
Corona Australis may have been documented in the MUL.APIN as the constellation MA.GUR by ancient Mesopotamians ("The Bark"). This constellation is close to SUHUR.MASH ("The Goat-Fish," modern Capricornus), could have been modern Epsilon Sagittarii instead. MA.GUR was one of the fifteen "stars of Ea" in the southern sky. (Rogers 1998) The Greek didactic poet Aratus wrote of but did not identify, the constellation in the third century BC, instead referring to the two crowns as o. (Stephanoi). The constellation was first described in the 2nd century AD by the Greek astronomer Claudius Ptolemy, who included Alpha Telescopii, which has since been shifted to Telescopium. He named the constellation (Stephanos notios), "Southern Wreath," after assigning thirteen stars to it, but other authors identified it with either Sagittarius (having fallen off his head) or Centaurus; with the former, it was termed Corona Sagittarii. (Allen 1963) Corona Australis was also known as the "Golden Crown of Sagittarius" by the Romans. (Simpson 2012) In the fifth century, it was known as Parvum Coelum ("Canopy," "Little Sky"). Sertum Australe ("Southern Garland") was given to it by French astronomer Jérôme Lalande in the 18th century. (Motz & Nathanson 1988) and Orbiculus Capitis, whereas Philippus Caesius, a German poet and author, termed it Corolla ("Little Crown") or Spira Australis ("Southern Coil") and related it to the New Testament's Crown of Eternal Life. Julius Schiller, a seventeenth-century celestial cartographer, related it to Solomon's Diadem. Allen 1963) Corona Australis was not always the wreath of Sagittarius, but arrows in his hand. (Motz &Nathanson 1988) The tale of Bacchus and Stimula has been linked to Corona Australis. Juno was enraged because Jupiter had impregnated Stimula. Juno persuaded Stimula to request Jupiter's entire glory, which the mortal woman could not endure and caused her to burn. Bacchus, Stimula's unborn child who grew up to be the god of wine, paid tribute to his mother by putting a wreath in the sky. (Staal 1988) The stars of Corona Australis are placed within the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ) in Chinese astronomy. (AEEA 2006) The constellation was known as ti'en pieh ("Heavenly Turtle") and signalled the start of winter during the Western Zhou dynasty. However, as time passed, the "Heavenly River" (Milky Way) became a more precise marker for the ancient Chinese, and therefore the turtle was replaced in this function. (Porter 1996) Al ubbah "the Tortoise," Al Ĥibā "the Tent," and Al Udḥā al Na'ām"the Ostrich Nest" are some of the Arabic names for Corona Australis. (Allen 1963) It was then given the Al Iklīl al Janūbiyyah, which was transliterated as Alachil Elgenubi, Elkleil Elgenubi, and Aladil Algenubi by European authors Chilmead, Riccioli, and Caesius. (Allen 1963) |
It was Won, a boomerang thrown by Totyarguil, to the Indigenous Boorong people of northwestern Victoria (Altair). (Hamacher & Frew 2010) Corona Australis was viewed by the Aranda people of Central Australia as a coolamon carrying a baby that was accidentally thrown to Earth by a group of sky-women dancing in the Milky Way. Gosses Bluff crater, 175 kilometres west of Alice Springs, was formed by the coolamon's impact. (Hamacher & Frew 2011) Corona Australis was seen by the Torres Strait Islanders as part of a bigger constellation that included part of Sagittarius and the tip of Scorpius' tail, as well as the Pleiades and Orion. Tagai's boat, crewed by the Pleiades, known as the Usiam, and Orion, known as the Seg, was visible in this constellation. Tagai oversaw this canoe, according to legend, but his crew members consumed all the goods on board without asking permission. Tagai was furious, so he bound the Usiam with a rope and fastened them to the boat's side, then flung them overboard. Scorpius' tail depicts a suckerfish, while Eta Sagittarii and Theta Coronae Australis mark the bottom of the canoe. (Staal 1988) Tanuma was the name given to the figure of Corona Australis on the island of Futuna, while Na Kaua-ki-Tonga was given to it in the Tuamotus. (Makeemson 1941)
Features
Corona Australis, while not a brilliant constellation, is notable for its easily recognised pattern of stars (Ridpath & Tirion 2017), which has been described as horseshoe- (Falkner 2011) or oval-shaped. (Malin & Frew 1995) It features twenty-one stars visible to the naked eye, despite having no stars brighter than fourth magnitude (brighter than magnitude 5.5). (Bakich 1995) Nicolas Louis de Lacaille labelled the constellation's most prominent eleven stars with the Greek letters Alpha through Lambda, skipping Iota entirely and naming two stars as Eta. Mu Coronae Australis, a yellow star with a spectral classification of G5.5III and an apparent magnitude of 5.21, was discovered by Johann Elert Bode and named by Benjamin Gould because it was brilliant enough. (Wagman 2003) |
Corona Australis Molecular Cloud
A black molecular cloud just north of Beta Coronae Australis is known as the Corona Australis Molecular Cloud. The cloud fans out from Epsilon Coronae Australis eastward along the constellation border with Sagittarius, illuminated by several embedded reflection nebulae. It contains 7000 M, Herbig–Haro objects (protostars), and some incredibly young stars (Malin 2010), and is one of the closest star-forming areas to the Solar System, at 430 light-years (130 parsecs) on the Local Bubble's surface. Johann Friedrich Julius Schmidt discovered the first cloud nebulae in 1865. (Steinicke 2010) The cloud contains the dark nebula and star-forming area Bernes 157, which is located between Epsilon and Gamma Coronae Australis. It has a diameter of fifty-five by eighteen arcminutes and numerous stars of brightness thirteen or higher. Because of the obscuring dust clouds, these stars are dimmed by up to eight magnitudes. (Bakich 2010) The Coronet cluster (also known as R CrA Cluster) is located near the centre of the active star-forming zone and is utilised to study star and protoplanetary disc development. (Sicilla-Aguilar et al., 2008) R Coronae Australis (R CrA) is a variable star with a magnitude ranging from 9.7 to 13.9. (O’meara 2002) It has the spectral type B5IIIpe and is blue-white. It is an incredibly young star that is still acquiring interstellar material. (Malin 2010) It is veiled by and illuminated by, the surrounding nebula, NGC 6729, which brightens and darkens with it. (O’Meara 2002) The nebula's length is five times its width, making it look like a comet in a telescope. (Motz & Nathanson 1991) |
A young variable star, TY Coronae Australis, illuminates another nebula, the mirror nebula NGC 6726/NGC 6727, to the north. The brightness of TY Coronae Australis changes sporadically between magnitudes 8.7 and 12.4, and the nebula's brightness varies as well. (O’Meara 2002) It has the spectral type B8e and is blue-white. R, S, T, TY, and VV Coronae Australis, the region's greatest young stars, are all ejecting material jets that force surrounding dust and gas to combine and produce Herbig–Haro objects, many of which have been detected nearby. (Wang et al., 2004)
The globular cluster NGC 6723, which can be seen next to the nebulosity in the neighbouring constellation of Sagittarius but is much further away, is not part of it. (Coe 2007)
The globular cluster NGC 6723, which can be seen next to the nebulosity in the neighbouring constellation of Sagittarius but is much further away, is not part of it. (Coe 2007)
Deep-sky Objects
IC 1297 – Planetary Nebula
NGC 6768 – Merging Galaxies (one Elliptical, the other Lenticular)
ESO 281-SC24 – Open Cluster
NGC 6541 – Globular Cluster
Bordering
constellations
Main stars - 6
Bayer stars - 14
Stars with planets - 2
Stars brighter than magnitude 3.00 - 0
Stars within 32.62ly - 0
Meteor showers
Corona Australids – mid-March – 4-6 per hour
IC 1297 – Planetary Nebula
NGC 6768 – Merging Galaxies (one Elliptical, the other Lenticular)
ESO 281-SC24 – Open Cluster
NGC 6541 – Globular Cluster
Bordering
constellations
- Sagittarius
- Scorpius
- Ara
- Telescopium
Main stars - 6
Bayer stars - 14
Stars with planets - 2
Stars brighter than magnitude 3.00 - 0
Stars within 32.62ly - 0
Meteor showers
Corona Australids – mid-March – 4-6 per hour