Super light exotic

New cotton candy planet leaves researchers puzzled

Astronomers have discovered a fourth "cotton candy" planet (the image shows an artist's impression) around the sun-like star Kepler-51a.

(Bild: NASA/ESA, L. Hustak, J. Olmsted, D. Player und F. Summers (STScI))

With the help of the Webb space telescope, astronomers have discovered a fourth so-called cotton candy planet around a young star called Kepler-51. The discovery makes the system, which is difficult to explain using conventional models, even more puzzling.

The scientists from Pennsylvania State University had actually wanted to use NASA's James Webb Space Telescope (JWST, "Webb" for short) to study Kepler-51d, the third planet in the system, in more detail. But to their surprise, it passed by its central star Kepler-51a two hours earlier than calculated.

Fourth planet discovered by chance
After analyzing archived and new data, the astronomers came to the conclusion that the most plausible explanation for this is the presence of a fourth planet whose gravity influences the orbits of the remaining three planets in the system around Kepler-51a.

The researchers believe that Kepler-51e has an orbital period of 264 days and a circular orbit slightly larger than that of Venus around our sun. According to the scientists, it is also a so-called cotton candy planet.

Puzzles about planetary lightweights
The discovery of the fourth cotton candy planet around Kepler-51a deepens the mystery surrounding these planetary lightweights. This is because the presence of Kepler-51e corrects the previous mass estimates slightly upwards. Nevertheless, these exoplanets are still too light for conventional models of planet formation.

Cotton candy planets are a class of exoplanets whose mass is only a few multiples of Earth's mass and which have a radius larger than that of Neptune. They have a very low average density (similar to cotton candy, hence their name; note).

(Bild: NASA-GSFC, Adriana M. Gutierrez (CI Lab) / Science Photo Library / picturedesk.com)

1.5 million kilometers from Earth
The "Webb" telescope (pictured above), which was also built with Austrian participation, was launched into space in December 2021 after decades of preparations and with some delay. It is now more than one and a half million kilometers away from Earth.

The observatory is intended to provide new images of the early universe with the help of a 25 square meter mirror, among other things. Astronomers hope that the telescope's images will provide insights into the time after the Big Bang 13.8 billion years ago, among other things. The lifespan of the JWST is initially set at ten years.