Two warm saturn-mass planets found orbiting the star TOI-3850

Star system: TOI-3850 | Distance from the Sun: 1572 light years

A multi-planet system has been identified orbiting TOI-3850, a G0 dwarf star similar in metallicity to our Sun. The system contains two warm planets—gas-rich worlds that orbit closer to their star than Jupiter, but further than the extremely hot planets commonly found in close proximity to their hosts. These planets are currently situated near a gravitational configuration known as a 2:1 mean motion resonance, where the outer planet completes one orbit for every two orbits of the inner planet.

The inner planet, TOI-3850 b, transits its host star, meaning it passes in front of the star from our perspective, allowing its size and orbital period of approximately 14.5 days to be measured. The outer planet, TOI-3850 c, does not transit; its presence and properties were identified using radial velocity, a method that detects the tiny gravitational tugs a planet exerts on its host star. Both planets have masses comparable to Saturn.

The planets are positioned just wide of a 2:1 orbital resonance, which suggests they may have moved inward toward the star through interaction with the original disk of gas and dust that formed the system. Calculations suggest that the non-transiting outer planet could begin to transit as viewed from Earth within the next few decades. Meanwhile, the inner planet is considered a prime candidate for future studies of its atmospheric composition.

Key findings
- TOI-3850 b is a transiting warm Jupiter-sized planet with an orbital period of 14.48 days.
- TOI-3850 c is a non-transiting companion with a mass similar to Saturn and an orbital period of 29.85 days.
- Both planets occupy a near 2:1 resonance, indicating a history of migration within the protoplanetary disk.
- TOI-3850 b is a candidate for detailed atmospheric characterization in future studies.
- The system shows transit timing variations with a 513-day super-period, helping to confirm the presence of the two-planet configuration.

Scientific study

A Pair of Warm Saturn-mass Planets near the 2:1 Mean Motion Resonance around TOI-3850 (external link)