Erakis

Source: (fr) Edmond Bernus & Ehya ag-Sidiyene, « Étoiles et constellations chez les Nomades, Awwal n° 5 (1989), pp. 141-153; CC-BY Roland Laffitte

The Garnet Star (rarely called Erakis, µ Cephei) is a star in the constellation of Cepheus. It's a red supergiant star of spectral type M2Ia. The star is very old; it has begun to fuse helium into carbon, whereas a healthy main sequence star fuses hydrogen into helium. At the ending of its life, it will go supernova, while probably can leave a black hole. Author: Francesco Malafarina (public domain = CC0).

The famous M-type supergiant variable star designated µ Cephei has two proper names listed in SIMBAD as of 2024: "Erakis" and "Herschel's Garnet Star". Both terms are incorrect, as Herschel did not name this star and "Erakis" is an uncommon transliteration variant of a star name that is applied somewhere else. The IAU WGSN, therefore, decided to drop this name for the IAU-CSN.

Etymology and History

The etymology of "Erakis" is shared with the name "Alrakis", which WGSN already adopted for the star µ Draconis A. Kunitzsch and Smart (2006) translate الراقص, ar-rāqiṣ, "the Trotting Camel." It forms part of an asterism in the Arabian sky. Transliteration (Romanization) from Arabic could be Arrakis or Alrakis, in English the latter variant is more common.

However, in some dialects of Arabic, e.g. in the Maghreb (northwest African areas), the "a" is not pronounced as a diphthong, and as there French is the second official language, people Romanize the Arabic letter "aleph" (ا) not with (French) "a" but with "e" (to be distinguished from French è and é). Hence, the variant Er(r)akis may also be valid, although not standard.

Misapplication of the Arabic

Becvar appears to have mistakenly attributed this variant of the name (Erakis) to µ Cephei instead of µ Draconis. No evidence for association of the name with µ Cephei has been found in pre-Becvar works. Becvar's name "Erakis" and its association with µ Cephei only appeared rarely in subsequent works (e.g. Rhoads 1971, Bakich 1995).

Star Name for µ Cep

Piazzi partially Latinized Herschel's English term "garnet" in his Palermo atlas (1814). Although Herschel did not name the star but only described it as "garnet red", Piazzi used the Latin term "Garnet Sidus" like a star name in his catalogue. Some recent works have the latter as "Garnet Star" (Burnham 1978; Hoffleit & Warren 1991 Bright Star Catalog, 5th ed.; Ridpath & Tirion 2007) or "The Garnet Star" (Kunitzsch & Smart 2006).

IAU Working Group Star Names

To reduce confusion in astrophysics research papers, the two names for µ Cep were discussed by the IAU WGSN in 2024 with the goal to decide for one of them. Erakis was *not* approved!

"Erakis" has a shared etymology with "Alrakis" which WGSN applied to µ Dra A so that a re-application would be a repetition. Furthermore, recent works Burnham 1978; Hoffleit & Warren 1991 Bright Star Catalog, 5th ed.; Ridpath & Tirion 2007, Kunitzsch & Smart 2006) prefer Piazzi's term "Garnet Star". Therefore, WGSN decided to adopt only this term in the IAU-CSN (and to drop the historical alternative "Erakis").