Coma Berenices (πλόκαμος)

Authors: Susanne M Hoffmann, Youla Azkarrula, IanRidpath

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Coma Berenices, modern boundaries, IAU and Sky & Telescope.

Photograph of the Coma star cluster. This file is from Wikimedia Commons and may be used by other projects. Open cluster Melotte 111, or Coma Star Cluster. http://sternwarte-kempten.de/

One of the 88 IAU constellations. The ancient "Greek" constellation originates from Egypt. It has been invented by Konon, the royal astronomer of king Ptolemy III and it was named after the king's wife, Queen Berenice II Euergetis as reported by Eratosthenes. However, the asterism always used to have names in other cultures. In this area of the sky close the pole of the ecliptic, there are not many bright stars, but a clearly recognizable star cluster of triangular shape (the visual appearance is an isosceles triangle).

Etymology and History

This figure has only been regarded as a constellation since Tycho Brahe included it in his catalogue in 1602, but the figure itself is ancient. It is treated as an association of faint stars in the constellation Leo; in the Almagest, for example, it is described as a ‘nebulous mass’ representing a ‘curl’.

The Almagest does not define whose curly hair is being represented here. It is not mentioned in Aratos, but the figure appears in Eratosthenes. Interestingly, he mentions it twice and somewhat confusedly:  In one of the two surviving text versions of Eratosthenes on the lion, there is a supplement to the list of stars in which he speaks of a triangle of stars next to the lion's tail and calls it the ‘curl of Berenice’. However, the fact that he also mentions a curl in the constellation of the Northern Crown – the curl of Ariadne – causes more confusion. Philologists therefore speculate whether, after Berenice II was removed by her son for political reasons, it was not appropriate for a time to speak of the "Lock of Berenice". There are astronomical reasons against this, but if the curl was – at least temporarily – assigned to Ariadne, this was not permanent, as the cult of Berenice subsequently became more important.

Origin of Constellation

Berenice was the name of several queens of Egypt. According to Eratosthenes, this refers to Berenice II Euergetis, the wife of the Greek ruler Ptolemy III. The royal couple were already revered for their charity during their lifetime: they were regarded as a pair of gods in Egypt and worshipped in Crete and Athens. The constellation is said to have been invented by Konon of Samos in 241 BCE. While Eratosthenes worked as a librarian and teacher of princes in Alexandria, Konon was the king's astronomer.

In Mesopotamia, the panicle of the date palm of the goddess Erua was in this place - neither a tuft of hair nor a curl of a queen.

Babylonian

• Erua's date palm branch/leaf/spadix
• Sissinnu Erua

Almagest

id	Greek (Heiberg 1898)	English (Toomer 1984)	ident.
		asterism of the The Lock/ The Ivy Leaf in Leo
33	τῆς μεταξὺ τῶν ἄκρων τοῦ Λέουτος καὶ τῆς Ἄρκτου κεφελοειδοῦς σοστροφῆς καλουμένου Πλοκάμου τὸ βορειότατον	The northernmost part of the nebulous mass between the edges of Leo and Ursa [Major], called Coma [Berenices]	15 Com
34	τῶν νοτίων τοῦ Πλοκάμου ἐξοχῶν ἡ προηγουμένη	The most advanced of the southern outrunners of Coma	7 Com
35	ἡ ἐπομένη αὐτῶν ἐν σχήματι φύλλου κισσίνου	The rearmost of them, shaped like an ivy leaf	23 Com

Convex Hull for the stars inside Plokamos (CC BY Youla Azkarrula).

Stars within the Constellation Area

id	Label	IAU design.	description	Vmag
1	γ Comae Berenices	HIP 60742	Constellation lines (Vertex)	4.34
2	Phyllon Kissinou	HIP 61394	Constellation lines (Vertex)	4.773
3	12 Com A	HIP 60351	Constellation lines	4.81
4	7 Com	HIP 59847	Constellation lines (Vertex)	4.86
5	14 Com	HIP 60697	Constellation lines	4.95
6	16 Com	HIP 60746	Inside the hull	4.959
7	13 Com	HIP 60514	Inside the hull	5.18
8	17 Com	HIP 60904	Inside the hull	5.236
9	21 Com	HIP 61071	Inside the hull	5.436
10	18 Com	HIP 60941	Constellation lines	5.468
11	-	HIP 60170	Inside the hull	5.51
12	4 Com	HIP 59468	Constellation lines (Vertex)	5.62
13	-	HIP 59923	Constellation lines (Vertex)	5.7
14	-	HIP 59364	Constellation lines (Vertex)	5.987
15	-	HIP 60599	Inside the hull	6.02
16	-	HIP 60168	Inside the hull	6.1
17	-	HIP 60327	Constellation lines	6.162
18	-	HIP 60098	Inside the hull	6.37
19	FM Com	HIP 60066	Inside the hull	6.433
20	-	HIP 59489	Constellation lines (Vertex)	6.457

Greek Mythology

The contemporary poet Kallimachos described why Konon invented the constellation, and the Roman poet Catullus translated it into Latin around 200 years later.

Berenice was a princess from Cyrene who married the king of Egypt in 246 BCE. The same year, he went to war against the Seleucids in the Third Syrian War. Eratosthenes, who also came from Cyrene but was now working in Athens, was brought in as tutor to the princes when their son Ptolemy IV Philopator was born in 245 BCE. However, Berenice prayed that her husband would return from the war in one piece and vowed to sacrifice her head of hair (or a lock of it) as soon as this happened.

On the king's return, she cut her hair and brought it to the temple of Arsinoë. Disturbance ensued when it disappeared the following day. Konon showed the excited crowd, which had gathered suspiciously, that the gods had moved the hair of the benevolent queen to the sky.

Nowadays, the constellation is often used for romantic narratives: As a constellation symbolising conjugal love and fidelity, it can be wonderfully used in planetariums and other contexts.

Names of the Star Cluster in other cultures

1. Aldafirah (Arabic - translation from Greek)
2. Awarhakoya (Locono People, South America)
3. Fatana-lua (..., Tonga/ Polynesia)
4. Hulbatalasad (Arabic Indigenous)
5. Itua ni Bure (..., Gilbert Is./ Micronesia)
6. Kinallaub (Kankanaey People, Philippines)
7. Langwei (郎位) (Chinese)
8. Phyllonkissinou (Ancient Greek)
9. Plokamos (Ancient Greek)
10. Sissinnu (Akkadian/Babylonian)
11. Te Yiku-o-te-kiole (Pukapuka, Cook Islands/ Polynesia)

Images from different cultures

• 
  Spirit of the Awarra Palm: constellation of the Lokono People in South America. Screenshot from Stellarium (2024), sky culture produced by Konrad Rybka.
• 
  Sissinu: the branch/ frond/ spadix of the date palm in Babylonian astronomy
• 
  Babylonian Goddess Erua with a frond and a spadix of a date palm (drawn in a map by Papke 1987).
• 
  Asterism of the Ivy Leaf as described in Ptolemy's Almagest (Stellarium 2024)
• 
  The Tassel (Arabic Indigenous constellation) of the Lion, screenshot from Stellarium (by Khalid al-Ajaji)
• 
  Chinese constellation Langwei (reconstructed by Boshun Yang)

Weblinks

• Ridpath, Ian, “Star Tales: online edition”.

References

• References (general)
• References (Babylonian)
• References (ancient Greco-Roman)
• References (medieval)