royal star

plural royal stars

1. astrologyOne of a set of four first-magnitude stars, Aldebaran, Regulus, Antares and Fomalhaut, regarded by ancient Persians as the guardians of the sky.

   The Eagle was perhaps associated with the ancient zodiac by virtue of its ‘royal star’ Altair.

   1998, John H. Roger, “Origins of the ancient constellations: I. The Mesopotamian traditions”, in Journal of the British Astronomy Association, volume 108, number 1, page 25, column 2

   2 more examples

   At the earlier period the Summer solstice was in the centre of Leo, the Autumnal equinox in the centre of Scorpio, and the Winter solstice in the centre of Aquarius - corresponding roughly, Mr. Maunder points out, to the positions of the four "Royal Stars," Aldebaran, Regulus, Antares and Fomalhaut.

   1920, Edward Carpenter, Pagan and Christian Creeds, New York: Harcourt, Brace and Co., published 1921, page 41

   These constellations each contained first-magnitude stars (Aldebaran, Regulus, Antares and Fomalhaut), which were close to the cardinal points and became known as the Royal Stars in later Persia. [...] The four royal stars may be symbolised in Persepolis, in a vast bas-relief of a king slaying a griffin, which has the horns and body of a bull, mane and forelegs of a lion, tail of a scorpion, and wings and hindlegs of an eagle.

   1998, John H. Roger, “Origins of the ancient constellations: I. The Mesopotamian traditions”, in Journal of the British Astronomy Association, volume 108, number 1, page 24, column 2