Astronomers find exoplanet where algorithm dismissed Kepler data as false positive
Scientists have found an exoplanet 300 light-years from Earth based on data from the Kepler Space Telescope. Located in the habitable zone, it was initially ignored because a computer algorithm dismissed the peak brightness as a false positive.
Named Kepler-1649c, the planet has a radius 1.06 times that of Earth. The amount of light the planet receives from its star is about 75 percent of the amount of light the Earth gets from the sun. According to NASA, that means that the temperature on the planet could be comparable to that on Earth. Kepler-1649c orbits its star in 19.5 Earth days and is therefore relatively close to it. This star is a red dwarf. This type of star is much fainter and smaller than the average star and is estimated to be the most common in the galaxy. However, it is questionable whether life is possible, partly because red dwarf stars tend to emit huge stellar flares with deadly radiation relatively often due to their high activity.
The exoplanet was found based on data from the Kepler telescope that was decommissioned in October 2018. He used the transit method, in which the star and the Earth must lie in the plane of the exoplanet’s orbit. As soon as the exoplanet crawls in front of its star, a small dip in the brightness of that star is observable. In most cases, such small decreases in the brightness of stars have causes other than a sliding planet. Twelve percent of Kepler’s data is about exoplanets, and to separate the wheat from the chaff, scientists use a computer algorithm called Robovetter.
However, the Kepler mission has yielded an enormous amount of data, with the signals sometimes difficult to identify. So astronomers knew that there would be false positives, where the algorithm wrongly judges that a signal is not caused by an exoplanet. Previously, the Kepler False Positive Working Group was established to detect these errors. Based on the findings of this group of researchers, it now appears that Robovetter had misidentified the Kepler-1649c data.
Much is still unknown about Kepler-1649c, such as the composition of the atmosphere, which can affect the actual temperature on the planet. In addition, current calculations about the planet involve a large margin of error, which is normal in astronomy when studying objects so far away. In any case, based on the Kepler data, Kepler-1649c is the closest planet to Earth in terms of temperature and size combination.
The researchers published their discovery in the scientific journal The Astrophysical Journal Letters, under the title A Habitable-zone Earth-sized Planet Rescued from False Positive Status.
Artist’s impression of Kepler-1649c and the red dwarf star around which the planet orbits in 19.5 days