Alphecca — Star in Corona Borealis

Alphecca (also called Gemma) is the brightest star in Corona Borealis at magnitude 2.23. It is a spectroscopic binary consisting of a white main-sequence primary (A0V) and a yellow companion (G5V) orbiting each other every 17.4 days. Located about 75 light-years from Earth, the primary star has a luminosity of about 74 times solar. Alphecca is also an eclipsing binary — the fainter companion periodically passes in front of the primary, causing a barely detectable dip in brightness.

Alphecca is the gem of the small but elegant semicircular constellation Corona Borealis (the Northern Crown), located between Bootes and Hercules. The constellation's distinctive curved arc of seven stars is easy to spot, with Alphecca as the brightest in the middle. Best observed from May through September when the Northern Crown is high in the evening sky. The eclipsing nature cannot be detected visually.

The name Alphecca derives from Arabic 'al-fakkah,' meaning 'the broken' or 'the broken ring,' referring to the gap in the circlet of Corona Borealis. The alternate name Gemma is Latin for 'jewel,' reflecting its position as the brightest gem in the celestial crown. In Greek mythology, the crown represents the jeweled diadem of Ariadne, placed among the stars by Dionysus.