Magnitude 4.102 Apparent magnitude (V) 4.102 | ||
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Similar Alpha Coronae Borealis, Alpha Crateris, 46 Leonis Minoris, Alpha Columbae, Eta Lyrae | ||
Alpha Coronae Australis (α CrA, α Coronae Australis) is a star in the constellation Corona Australis. It is the only star in the constellation with a proper name, Alphekka Meridiana (Alphekka South), after the brightest star in Corona Borealis, Alphecca. In Chinese astronomy, it is known as 鱉六 (the Sixth Star of the River Turtle). It is a Class A star like Vega, rotating extremely fast on its axis, close to its breakup velocity.
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Properties
Alpha Coronae Australis belongs to the spectral class A2Va and has apparent magnitude +4.10. Located about 125 light years from Earth, the star's mass and radius are estimated at 2.3 times solar. With an effective temperature of roughly 9,100 K, the star radiates a total luminosity of about 31 times solar. This star is roughly 254 million years old. A rapidly rotating star, it spins at almost 200 km per second at the equator, making a complete revolution in approximately 14 hours. Like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust.
Etymology
The name Alphecca or Alphekka is Arabic, short for نير الفكّة nayyir al-fakka "the bright (star) of the broken (ring of stars)".
In Chinese, 鱉 (Biē), meaning River Turtle, refers to an asterism consisting of α Coronae Australis, α Telescopii, η1Coronae Australis, ζ Coronae Australis, δ Coronae Australis, β Coronae Australis, γ Coronae Australis, ε Coronae Australis, HD 175362, κ2 Coronae Australis and θ Coronae Australis. Consequently, α Coronae Australis itself is known as 鱉六 (Biēliù, English: the Sixth Star of River Turtle.).