Transit timing variations in HD 332231 b hint at a hidden planetary companion

Star system: HD 332231 | Distance from the Sun: 263 light years

HD 332231 b is a warm sub-Saturn exoplanet that orbits close to its host star. Astronomers studied the timing of its transits—when the planet passes in front of the star—and found that these events do not occur at perfectly regular intervals. Instead, the transit times show a repeating pattern, known as transit timing variations (TTVs), which can reveal the presence of other planets in the system.

Using precise data from the TESS mission and ground-based telescopes, the team measured each transit and built a diagram showing the differences from a regular schedule. They found a clear TTV pattern with a period of about 6.7 years and an amplitude of 45 minutes. Computer models suggest that these variations are likely caused by another, unseen planet orbiting farther from the star, possibly in a resonant orbit with HD 332231 b. The exact properties of this companion are still uncertain, but it is likely on an orbit longer than 60 days and may have a moderately to highly elongated path. Continued observations will help confirm the existence and nature of this hidden planet.

Key findings
- HD 332231 b shows periodic transit timing variations with a 6.7-year period
- The TTVs have an amplitude of about 45 minutes
- The variations suggest the presence of an external planetary companion
- The companion likely orbits beyond 60 days and may be in resonance with HD 332231 b
- Further monitoring is needed to confirm and characterize the additional planet

Scientific study

Detection of periodic transit timing variations in warm sub-Saturn HD 332231 b (external link)