Alpha Coronae Australis - Alfecca Meridiana

The α and β stars of Corona Australis, the Southern Crown, are both of magnitude 4.11. The Southern Crown lies south of Sagittarius, and may represent the centaur's crown. Its northern counterpart, Corona Borealis, is the Northern Crown of Aridane; its brightest star is named Alphecca.

The Alpha star of Corona Australis is known as Alfecca Meridiana, or "Alphecca south" (note the spelling change). In this context, "Meridiana," from Latin, refers to noon, when a resident of the northern hemisphere looks to the Sun in the south, leading to an alternative definition of "meridiana" as "southern."

Properties

α CrA is a rather ordinary class A1 V hydrogen-fusing star, with a surface temperature of 9100 K. At a distance of 130 light years, it shines with 31 times the luminosity of the Sun. Alfecca Meridiana is a fast rotator, spinning at least at 180 km/sec at its equator. With a radius 2.3 times solar, it makes a full rotation in under 18 hours (the Sun takes 25 days).

With a mass around 2.3 times solar, Alfecca Meridiana is about halfway through its hydrogen-fusing main-sequence lifetime, and will eventually evolve into a relatively heavy white dwarf.

Alfecca Meridiana is a single star, but radiates excess infrared radiation that seems to come from a surrounding disk of cool dust. Like Vega, this suggests of some kind of surrounding planetary system.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]