Analysis of TOI-1408 planetary system reveals significant uncertainties in planet properties

Star system: TOI 1408 | Distance from the Sun: 455 light years

The TOI-1408 system is known to host two planets in a 2:1 orbital resonance - meaning the inner planet completes two orbits for every one orbit of the outer planet - alongside a distant companion. A recent study of TESS space telescope data and ground-based observations has reassessed the system's configuration, finding that current measurements of the planets are influenced by complex factors in the data modeling.

Researchers found that the likelihood functions, which represent the probability of different model parameters, contain multiple possible solutions. This creates larger uncertainties in physical measurements than previously thought, particularly regarding the size of the inner planet.

Due to the near-tangential nature of the transit - where the planet grazes the edge of the star rather than crossing the center - the radius of TOI-1408 b remains poorly constrained, currently estimated between 1.2 and 3.5 times the radius of Jupiter. The study also highlights that model results are heavily dependent on how the mass and radius of the host star are initially defined.

The findings emphasize that without more precise correlations between the star's mass and radius, determining the exact properties of the orbiting planets remains difficult. Future efforts will need to better define stellar parameters to narrow down these wide margins of error.

Key findings
- The TOI-1408 system contains two planets in a 2:1 mean-motion resonance.
- Measurement uncertainties for TOI-1408 b are larger than previously estimated.
- The radius of TOI-1408 b is poorly constrained between 1.2 and 3.5 Jupiter radii due to its grazing transit geometry.
- Model results show a strong dependency on the chosen constraints for stellar mass and radius.

Scientific study

TOI-1408: the limb darkening models, photometric and Doppler noises, and the exoplanetary system (external link)