While ESA’s Cheops was examining two exoplanets, it also unexpectedly discovered an additional planet in a nearby star system that was not there the last time it was checked. The research team has concluded that this specific planet is unexpectedly different from all known planets.
“We set out to build on previous studies of Nu2 Lupi and observe planets b and c crossing the face of Nu2 Lupi with Cheops, but during a transit of planet c we spotted something amazing: an unexpected transit by planet ‘d’, which lies further out in the system,” explained lead author Laetitia Delre.
This exoplanet orbits a bright star visible to the naked eye. This star, located 50 light-years from Earth, is named Nu2 Lupi and it can be found in the constellation of Lupus. The researchers caught the planetary transit stage, which yields valuable scientific data about a planet’s physical characteristics. When a planet crosses in front of its star, the planet also blocks some of the star’s light.
Compared with most of the exoplanets that have been discovered, planet d has a fairly mild amount of stellar radiation. The Cheops exoplanet search instrument was used to find that the planet d has a radius of around 2.5 times that of Earth, taking just over 107 days to complete one revolution around its star.
“Combined with its bright parent star, long orbital period, and suitability for follow-up characterization, this makes planet d hugely exciting – it is an exceptional object with no known equivalent, and sure to be a golden target for future study,” added David Ehrenreich, the co-author of the study.
The results are significant and they indicate that Cheops has huge potential. The satellite is designed to collect precise data about stars and any planets orbiting them.