Two Six-Sun Systems

Two six-sun systems—Castor and ADS 9731.

Castor and ADS 9731

At least two systems in the Solar vicinity hold six suns in relatively stable orbits. These are the stars known as Castor (Alpha Geminorum; one of the Gemini twins), and ADS 9731 which is too dim to be a naked-eye star. From a recent study, ADS 9731 (HD 139691) proves to be moderately ancient at 2.8 billion years old—ripe for life, if it has any planets.