A new study published in the Astronomical Journal reveals a fourth low-density planet orbiting the 500-million-year-old G-type star Kepler-51. Located approximately 2,615 light-years away in the constellation of Cygnus, this star was already known to host three massive “super-puff” exoplanets.
The three previously discovered planets – Kepler-51b, c, and d – have orbital periods close to a 1:2:3 ratio, indicating they are several times the mass of Earth. Despite their size, these planets have extremely low densities, similar to cotton candy. The reason behind this unusual density is still unknown.
Researchers from Penn State University and Osaka University conducted an extensive analysis of transit timing data spanning over 14 years using facilities like the James Webb Space Telescope and other observatories. They discovered a fourth planet, Kepler-51e, with a mass similar to the previous three planets and a circular orbit of about 264 days.
While it is unclear whether Kepler-51e is also a “super-puff” planet due to lack of transit observations, the team found that its signal can be explained by this model. The study suggests that super-puff planets are relatively rare, with only one existing in most systems. This new discovery raises more questions about how these unusual planets formed and evolved.
The researchers emphasize the importance of continued observation of transit timing variations to discover more distant planets and potentially habitable worlds.
Source: https://www.sci.news/astronomy/kepler-51-system-fourth-exoplanet-13477.html