2023-11-06 10:44:45
Astronomers recently analyzed data collected by the Kepler telescope before its retirement in 2018. They identified an unusual system made up of seven planets destroyed by intense radiation from their parent star.
An exceptional discovery
Kepler was launched in 2009 with the primary mission of detecting exoplanets. To do this, he observed distant stars looking for variations in brightness that might indicate the presence of planets passing in front of their star from the telescope’s point of view. This mission will have resulted in the discovery of thousands of candidate exoplanets and hundreds of planetary systems.
Kepler has been retired since 2018 and has since been replaced by the TESS satellite. However, the data collected by the observatory continues to be examined.
More recently, astronomers have focused on a star located at a dizzying distance of 4,672 light years of the earth. Around it, the team would have identified no less than seven planets. This system, called Kepler-385, is one of the few known to host more than six planets. A famous example of a similar system is TRAPPIST-1 which has seven Earth-like worlds.
An illustration of the seven planets of the Kepler-385 system. Credits: NASA/Daniel Rutter
A very inhospitable system
At the heart of Kepler-385 is a star slightly larger and hotter than our Sun. The first planet, Kepler-385 b, is approximately 12.8 times more massive than Earth and 2.7 times wider. It orbits very close to its star, regarding 10% of the distance between Earth and the Sun, completing one orbit in just ten Earth days.
The next planet, Kepler-385 c, is a little larger than Earth and has a mass regarding 13.2 times that of our planet. This object follows an almost circular orbit, covering just 13% of the distance between Earth and the Sun, with an orbital period of just over fifteen Earth days.
These first two planets, Kepler-385 b and Kepler-385 c, are considered to be rocky planets with thin atmospheres. The remaining five planets in the system are farther from their star and are regarding twice the size of Earth. We think they are enveloped in thick atmospheres.
The central star of Kepler-385, although slightly larger and hotter than our Sun, emits an exceptionally high amount of radiation, particularly in the X-ray and ultraviolet range. In this system, each of these planets receives more radiation from its star than any planet in the solar system receives from the Sun.
High levels of radiation make unlikely the presence of life forms similar to those on Earth. However, astronomers are still interested in these extreme environments to better understand the diversity of possible planetary conditions.
A paper detailing the discovery is to be published in The Journal of Planetary Science. A version is nevertheless already available on the website préimpression arXiv.
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