Coma Berenices is an ancient asterism in the northern sky which has been defined as one of the 88 modern constellations. It is located in the fourth galactic quadrant, between Leo and Bootes, and is visible in both hemispheres. Introduced to Western astronomy during the third century BC by Conon of Samos, its name means "Berenice's Hair" in Greek (via Latin) and refers to Queen Berenice II of Egypt, who sacrificed her long hair as a votive offering. Coma Berenices is the only modern constellation named for an historic figure.
Three of constellation's stars are visible to the naked eye: Alpha Comae Berenices, Beta Comae Berenices and Gamma Comae Berenices.
Alpha Comae Berenices (Alpha Com, α Com, α Comae Berenices) is a star in the constellation Coma Berenices (Berenice's Hair). Although it has the Bayer designation "alpha", at magnitude 4.32 it is actually fainter than Beta Comae Berenices. It has the traditional name Diadem. It is said to represent the crown worn by Queen Berenice. A name occasionally seen is Al Dafirah, from the Arabic الضفيرة ađ̧-đ̧afīrah "the braid".
Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices. The star is similar to the Sun, being only slightly larger and brighter in absolute magnitude. In terms of age it is younger than the Sun, being about 3 billion years old.