As is common for long-period planets discovered around other stars, it has an orbital eccentricity greater than that of Jupiter.

[1] Preliminary astrometric measurements suggested that the orbital inclination is 170.3°,[5] yielding an object mass of 38 times that of Jupiter, which would make it a brown dwarf.

However, subsequent analysis indicates that the precision of the measurements used to derive the astrometric orbit is insufficient to constrain the parameters.

[6] A more plausible suggestion is that this planet shares its star's inclination, of 69+21−26°.

[7][8] In 2022, the inclination and true mass of 109 Piscium b were measured via astrometry.