Alpha Coronae Australis

Alpha Coronae Australis or α Coronae Australis, officially named Meridiana, is the brightest star in the constellation of Corona Australis. It is located about 125 light-years from Earth.

Nomenclature

α Coronae Australis is the star's Bayer designation.
It is the only star in the constellation with a traditional proper name, Alphekka Meridiana, after Alphecca, the brightest star in the constellation Corona Borealis. The name Alphecca or Alphekka is Arabic, short for نير الفكّة nayyir al-fakka "the bright of the broken ". In 2016, the IAU organized a Working Group on Star Names to catalog and standardize proper names for stars. The WGSN approved the name Meridiana for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, 鱉, meaning River Turtle, refers to an asterism consisting of Alpha Coronae Australis, Alpha Telescopii, Eta¹ Coronae Australis, Zeta Coronae Australis, Delta Coronae Australis, Beta Coronae Australis, Gamma Coronae Australis, Epsilon Coronae Australis, HD 175362, Kappa² Coronae Australis and Theta Coronae Australis. Consequently, the Chinese name for Alpha Coronae Australis itself is 鱉六.

Properties

Alpha Coronae Australis belongs to the spectral class A2Va, making it an A-type star like Vega. Like the latter, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It has an apparent magnitude of +4.10. The star's mass and radius are estimated at 2.3 times the Sun's mass and radius. With an effective temperature of roughly 9,100 K, the star radiates a total luminosity of about 31 times the Sun's. 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, close to its breakup velocity.