#hat-p-23

Delphinus, which is Latin for "dolphin," is the first of the constellations in the "Heavenly Waters" family. This is an area of sky between Sagittarius and Orion filled with dim constellations all associated with water thanks to the Mesopotamians.

Delphinus is one of the smaller constellations, but it is one of the original 48 constellations written about by Greek astronomer Ptolemy in the 2nd century. According to Greek mythology, this dolphin was sent out by Poseidon to find the nereid Amphitrite whom Poseidon wanted to marry. Delphinus did find Amphitrite and convinced her to accept Poseidon's hand in marriage.

There are several named stars here. In order of brightness:

Rotanev (β Delphini) is a binary star system consisting of two equally-bright yellow-white giant stars. The system lies about 101 light years away. Its name has an origin in a practical joke! The Italian astronomer Niccolò Cacciatore worked at and eventually led the Palermo Observatory. His boss, Giuseppe Piazzi published a star atlas, and attached to this star was the obscure name "Rotanev." Niccolò had added this name in honor of himself! His name in English was Nicholas Hunter, which is Latinized to Nicolaus Venator. "Venator" backwards is "Rotanev"!

Sualocin (α Delphini) is an octuple star system with a central triple system consisting of at least one blue-white giant. The entire system lies about 254 light years away. Its name shares its origin with Rotanev: "Sualocin" is "Nicolaus" backwards!

Aldulfin (ε Delphini) is a solitary blue giant star about 330 light years away. Its name comes from the Arabic phrase ðanab ad-dulfīn meaning "the dolphin's tail."

Musica (18 Delphini) is a binary star system consisting of a yellow giant and a red dwarf. The system lies about 245 light years away. It has one confirmed exoplanet orbiting it, about 9 times the mass of Jupiter, named Arion. Both names were given by the people of Japan: Musica is Latin for "music," while Arion is a Greek poet and musician who was supposedly saved at sea by dolphins.