A recent study published in The Astronomical Journal has revealed the discovery of a fourth planet in the Kepler-51 system, an already remarkable planetary system known for hosting three ultra-low-density “super-puff” planets. This discovery was made by a research team led by Dr Jessica Libby-Roberts, a postdoctoral fellow at Penn State’s Centre for Exoplanets and Habitable Worlds, and Dr Kento Masuda, Associate Professor of Earth and Space Science at Osaka University. The finding suggests that the gravitational influence of the newly identified planet, named Kepler-51e, explains unexpected variations in the transit timings of the system’s known planets.

Unexpected Findings During Observations

As per a report by Phys.org, the researchers initially aimed to study Kepler-51d using NASA’s James Webb Space Telescope (JWST) but observed its transit occurring two hours earlier than predicted. This significant deviation prompted further analysis of data from NASA’s Kepler and TESS telescopes, Hubble Space Telescope and ground-based observatories such as the Apache Point Observatory (APO) and Palomar Observatory, as per reports. According to the team, only a four-planet model could account for the observed transit timing variations.

Insights Into the Kepler-51 System

Kepler-51e is believed to have a mass comparable to the existing planets in the system, following a relatively circular orbit of approximately 264 days. However, its classification as a “super-puff” remains uncertain due to the lack of transit data needed to calculate its radius and density. The inner three planets, known for their extremely low densities, continue to intrigue scientists. The team noted that accounting for the fourth planet alters previously estimated masses of the inner planets, slightly increasing their values while maintaining their status as super-puffs.

Future Implications of the Study

Dr Libby-Roberts, in a statement, indicated the potential for further exploration, stating that Kepler-51e’s orbit, located just inside the system’s habitable zone, suggests the possibility of additional planets or complex gravitational interactions. Continued observations may uncover planets farther from the star, contributing to the search for potentially habitable worlds. Researchers are also analysing data from JWST to study the atmospheric composition of Kepler-51d, which may shed light on the formation mechanisms of such unusual planets.