It has an apparent visual magnitude of 6.81,[2] which lies below the limit of visibility for normal human sight.
The system is located at a distance of 133.5 light years from the Sun based on parallax.
[8] The star is radiating 2.69[6] times the luminosity of the Sun from its photosphere at an effective temperature of 5,921 K.[6] A red dwarf companion star was detected in 2005 with a projected separation of 3,898 AU.
[11] Since this planet was discovered by radial velocity, only its minimum mass was initially known, and there was a 5% chance of it being massive enough to be a brown dwarf.
[10] In 2023, the inclination and true mass of HD 213240 b were determined via astrometry, confirming its planetary nature.