The planets, a super-Earth and a "mini-Neptune" are unusual in that they have very close orbits; their semi-major axes differ by only 0.013 astronomical units, meaning that their interaction causes extreme transit timing variations for both.
The planets, a super-Earth and a "mini-Neptune" are unusual in that they have very close orbits; their semi-major axes differ by only 0.013 astronomical units. Coupled with masses significantly higher than Earth, their gravitational influence to each other is significant, meaning that their interaction causes extreme transit timing variations for both.