Third hidden planet perturbs the orbit of two known planets around Kepler-50

Star system: Kepler-50 | Distance from the Sun: 823 light years

The star Kepler-50 hosts two known planets that pass in front of their host star from our perspective, an event known as a transit. These two planets are locked in a near-resonant relationship, meaning their orbital periods are mathematically related. Analysis of their transit times reveals small, irregular timing variations, which indicate the presence of a third, non-transiting planet tugging on them through gravity.

Researchers examined data from the Kepler space telescope using dynamical modeling to account for these gravitational interactions. By studying the transit timing variations, they were able to calculate the physical properties of the inner planets despite the presence of the hidden third world.

The study determined that the two transiting planets, Kepler-50 b and c, have masses of 2.35 and 4.43 times that of Earth. Their sizes place them within the radius valley and the sub-Neptune category, respectively. The non-transiting planet's exact characteristics remain uncertain due to multiple potential configurations that could cause the observed orbital fluctuations.

Key findings
- Two transiting planets, Kepler-50 b and c, have determined masses of 2.35 and 4.43 Earth masses.
- Gravitational disturbances confirm the presence of a third, non-transiting planet in the system.
- The two known planets exhibit non-zero relative eccentricity, meaning their orbits are not perfectly circular.
- Planet b and c measure 1.75 and 2.08 Earth radii, placing them in the radius valley and sub-Neptune size ranges.
- The system serves as a significant benchmark for understanding planet formation due to the close proximity and orbital resonance of the planets.

Scientific study

Kepler-50: Two Planets in Close Resonance Perturbed by a Non-transiting Planet (external link)