Collège St JUERY / 81160 St JUERY /  FRANCE


~ Constellation Coma Berenice ~



I - The constellation Coma Berenice

Coma berenice is a small boreal constellation. In the past, this constellation was the tuft of hair at the extremity of  the Leo's tail.

Identity card :
- name : Coma berenice
- English name : Berenice’s Hair
- abrevation : Com
- size : 42
- RA : 13 hours
- decl. : +25 degrees
- season : Spring
stjuery_berenice03.gif (1749 octets)

Coma Berenice is between four constellations : Cames Venatici to the north, Virgo to the south, Leo on the west and Bootes on the east.


II - Legend

The constellation were named by the royal Greek astrologer Conon of Samos (247 BC) after the hair of Egyptian Queen Berenice. She was the wife of Ptolemy III and the daughter of Magas of Cyrene. When King Ptolemy III went to war against Seleucos, the king of Syria, Berenice promised her hair to
Aphrodite, the Greek goddess of love and beauty, if her husband returned safely and victorious. After the king's return, Berenice, condemned by her wish, cut her hair though loss was hard. The next day, when the king went to have a look at his wife's hair, he was furious to find that the hair had be stolen. But at nightfall, Conon of Samos showed the king the new constellation in the sky. The astrologers said that the goddess Aphrodite had placed her tresses among the stars and King Ptolemy III was satisfied.

stjuery_berenice01.gif (60945 octets)


III - Stars and object in Coma Berenice
Coma Berenice is a constellation that consists of a multitude of sky objects (stars, galaxies, star clusters and galaxy cluster).



The three main principal stars in Coma Berenice are alpha Comae, beta Comae and gamma Comae. These three stars form a nearly perfect right-angled triangle but they are not very visible..

  • Alpha Comae is called diadem. This star has the same diameter as our Sun.
  • Beta Comae is the brightest star in this constellation. It also has a diameter equal to our sun. This star is probably more active to the sun.
  • Gamma Comae is an orange star. It is near to the Coma star cluster.


Star Decl. Lat. Mag. Sp.
Alpha Comae +17 47 48 +22 58 49 4,32 F4
Beta Comae +28 07 52 +32 30 26 4,32 G0
Gamma Comae +28 32 48 +28 24 00 4,56 K3

Alpha comae as well as zeta Comae, 17 Comae and 24 Comae, 35 Comae, Struve 1633 and Struve 1939 are double stars in Coma Berenice.




In Coma Berenice are many objects, particulary in the southern regions, near to the constellation Virgo. This constellation counting eight Messier’s objects among are seven galaxies around 10 to 50 million light years away.


Main principal objects in comma Berenice :

- Spiral galaxie : M64, M88, M91, M98, M99, M100
- Eliptical galaxie : M85
- Globular custer : NGC 5053, M53
- Open star cluster : Mel 111
Name Size Magnitude
M64 (NGC 4826) 9,3' x  5,4' 9,08
M85 (NGC 4382) 7,4'  x  5,5' 10,07
M88 (NGC 4501) 6,9'  x  3,9' 10,31
M91 (NGC 4548) 5,4'  x  4,4' 11,04
M98 (NGC 4192) 9,5'  x  3,2'  10,71
M99 (NGC 4254) 5,4'  x  4,8' 10,17
M100 (NGC 4321) 6,9'  x  6,2' 10,26
M53 (NGC 5024) 12,6' 7,8
NGC 5053 10,5' 9,8
Mel 111 275,0' 1,8


IV- Exercice
The observation must to take part in Spring. For study Coma Berenice, you will have a dark night because stars that form this constellation aren’t very prominent
Put on this sketch then in the sky the name of these three stars :
  • Alpha Comae
  • Beta Comae
  • Gamma Comae
stjuery_berenice02.jpg (62609 octets)


Follow this indications :

Locate stars Denebola (Constellation Leo) on the west and Arcturus (contellation Bootes) on the east. From Denebola, draw a line to Arcturus, alpha Comae is in the middle of this line. The star to the north of alpha Comae is beta Comae. To the west of beta Comae, next to the constellation Leo, there is gamma Comae.

Alpha Comae, beta Comae and gamma Comae form a perfect triangle.


V- Bibliography
  • Dictionnaire de L’Astronomie et de l’espace / Philippe de la Cotardière – JP Penot
  • Astronomie Astrophysique / Marc Séguin – Benoit Villeneuve
  • A l’affut des étoiles / Pierre Bourge – Jean Lacroux
  • Thanks to Media Library - St Juery