K2-288Bb is within a binary system of two red dwarfs. The primary, K2-288A, is 52% the mass and 45% the radius of the Sun, while the secondary, K2-288B, is 33% the mass and 32% the radius. They are both much cooler and dimmer than the Sun, with temperatures of 3584 K and 3341 K, and are 0.03236 and 0.01175 times as luminous as the Sun, which has a temperature of 5772 K. Both stars are also rather metal-poor, with metallicities of -0.29 [Fe/H] for the primary, and -0.21 [Fe/H] for the secondary. In comparison, the Sun has a metallicity of 0.00 [Fe/H]. K2-288A and K2-288B orbit each other at a distance of about 55 AU, around six times the distance from Saturn to the Sun.
