HD 110067 e is the smallest of six sub-Neptunes, planets between Earth and Neptune in size, that transit HD 110067, a star a little smaller than the Sun about 100 light-years away. It is about 1.94 times Earth's width and orbits every 30.8 days, the fourth planet out.
It was one of the three outer planets predicted rather than simply spotted. After a team led by Rafael Luque used ESA's CHEOPS satellite to show that the inner three planets orbit in a 3 to 2 rhythm, they used that pattern to work out where further planets should be, and matched the predictions to the remaining dips in NASA's TESS data. HD 110067 e continues the chain: its period is about one and a half times that of d, the last of the three 3 to 2 steps, before the outer two pairs switch to a 4 to 3 rhythm. Counted from the inside, the innermost planet completes six orbits for every one of the outermost.
Its mass has not been measured; the discovery team could set only an upper limit from the star's wobble. In 2024 a team led by Caleb Lammers showed that the chain is almost certainly in true resonance, because nonresonant versions of the system nearly always fall apart within 25 million years, a tiny fraction of its age. Assuming resonance, they set lower limits on the unmeasured masses, including HD 110067 e's. It receives about 14 times the light Earth gets from the Sun, too much for liquid water.