STT 81 (56 Persei) is likely a quadruple system located 132 light-years away. The primary component A is a binary system consisting of a yellow-white main sequence star of spectral type F4V with a mass of 1.5 solar masses and a radius of 2 solar radii (Aa). The companion (Ab) is a white dwarf of spectral type DA3.1 with a mass of 0.6 solar masses. The orbital period of components Aa and Ab is 47.3 years, and they are, on average, separated by 17.6 AU. The companion B is a star with a mass of 0.84 solar masses and is located 178 AU from component A. In the WDS, component B is classified as a binary star with a companion of 11.3 magnitude.

103mm - 56 Persei is a distinctly resolvable pair in medium-sized telescopes, while in smaller ones, the resolution may be somewhat more challenging. I observed the primary component as yellow-white and the secondary as gray.