- ALPHECCA or GEMMA (Alpha Coronae Borealis). One of the very few stars with two commonly used names, Alphecca is the dominant (mid- second magnitude, 2.23) Alpha star of the delightful constellation Corona Borealis, the Northern Crown, a semicircle of stars to the east of Arcturus that truly reminds the viewer of a heavenly crown, the constellation representing the crown of Ariadne.