Alpha1 Capricorni


Alpha1 Capricorni, Latinized from α1 Capricorni, is a distant likely multiple star system dominated by a highly luminous star in the constellation of Capricornus yet north of the ecliptic. It also has the traditional star names Prima Giedi and Algiedi Prima. It is approximately 870 light years from the solar system. It is separated from the brighter Alpha2 Capricorni by 0.11° of the sky, a gap resolvable with the naked eye, similar to Mizar and Alcor and both are not to be confused with much fainter 3 Capricorni nor somewhat fainter Nu Capricorni which are 3 to 6 times the angular distance of that separating the two Alpha stars, respectively.
α1 Capricorni has three faint possibly slow co-orbiting stars within one arc-minute, so unresolveable to small telescopes. The brightest of these is 10th magnitude and on this basis it has often been considered as an optical binary. Separation is increasing rapidly due to great proper motion of the primary star. The Hipparcos satellite in about the year 2000 found an undetected very close companion, 0.6" away and four magnitudes fainter.
The primary star is a yellow G3 supergiant with an apparent magnitude of +4.3. This star has 5.3 times the mass of the Sun and is radiating around 1,047 times the Sun's luminosity.

In popular culture

The name Giedi Prime is used for a fictional planet in Frank Herbert's 1965 science fiction novel Dune. This Giedi Prime is a planet of the star 36 Ophiuchi B, and is the home world of the villainous House Harkonnen.