OGLE-TR-122 is a binary stellar system containing one of the smallest main-sequence stars whose radius has been measured.

It was discovered when the Optical Gravitational Lensing Experiment (OGLE) survey observed the smaller star eclipsing the larger primary.

The system's primary is thought to resemble the Sun.

[2] The smaller star, OGLE-TR-122B, is estimated to have a radius around 0.12 solar radii, or around 20% larger than Jupiter's, and a mass of around 0.1 solar masses, or approximately 100 times Jupiter's.

[4] The observed transit provides the first direct evidence for a star with a radius comparable to Jupiter's.