Hydor

The Ancient Greek term Hydor (ὕδωρ) means "Water". It is a constellation that is only mentioned in Aratus' didactical poem "Phainomena".

Etymology and History

Star Name

"Hydor" - water - is the first name listed in Allen (1899) although not transliterated from the Greek to Latin alphabet: "λ, 3.8, red, is the most prominent of the first stars in the Stream. Proclus followed Aratos in calling it Ὕδωρ, [note: Hydor] the Water; and others, Ἔκχυσις, [note: "Ekkhysis"] the Outpouring; Aratos describing it, "Like a slight flow of water here and there, Scattered around, bright stars revolve but small"; although these titles, appropriated by Bayer for λ, originally were for the whole group set apart as the Stream. Allen's description basically repeats Bayer (1603) Uranometria, attributing names to Aratus and Proclus.

However, the entry is one of many sloppinesses in Allen (1899). The term "Hydor" describes the whole huge region of faint stars around Cetus - it is the element that makes the monster depicted in Cetus a seamonster (because it is in Hydor!). This way, the constellation Hydor is depicted on all three surviving globes from antiquity!

IAU Working Group Star Names

As the term Ὕδωρ originally describes a constellation and, thus, a group of many faint stars or an area in the sky, we can apply the name to any star in that area around the figure of Cetus (in Eridanus, Fornax, Cetus, Sculptor, Aquarius - although "For" doesn't make sense). The name "Hydor (ὕδωρ) is suggested for 2 Cet (HIP 301, HR 9098 SIMBAD), a blue star (B9) of 4.536 mag in visible light. In modern star charts, the star is located between the tail of the Cetus-figure and the drops of the outlet of Aquarius.

the WGSN chose ... (not to apply/ to apply the name to a neighbouring star/ to ...) in the IAU-CSN.