Astronomers from the Massachusetts Institute of Technology, the University of Wisconsin and a group of amateur scientists may have discovered the last planets observed by the Kepler telescope, before it ceased operation in 2018. Analyzing data from its latest observing campaign, experts collected data from 500,000 stars, until it ran out of fuel. “We were curious to see if we could get anything useful out of this small data set and tried to see what last piece of information we could extract from it“explained Andrew Vanderburg, an assistant professor at MIT. To that end, he and Elyse Incha, lead author of the study describing the findings, presented the challenge to members of the Visual Survey, a group of amateur and professional astronomers.
Together they searched for possible exoplanets in satellite data by analyzing the light curves of each observed star. “We differentiated the data from nuisances such as instrument failures“, he added Vanderburg. This is how they spent a few days analyzing the light curves of quasi 33,000 digits. Working with high-quality data obtained in the week before the telescope went out of focus, the researchers found planetary transit signals on three different stars. Planetary transit occurs when a planet passes in front of its star, temporarily obscuring it. Eventually, the team found two planets and confirmed them with data from the TESS telescope. One is K2-416 b, a world 2.6 times the size of Earth that orbits its star every 13 days. K2-417 b is almost three times larger than the Earth and completes one revolution around the star every 6.5 days. Finally, another star has the candidate planet EPIC 246251988 b, which, however, still needs to be confirmed with new observations. “We found what are probably the last planets discovered by Kepler, in data taken when he was at the end of his activity“Vanderburg concluded. The results were described in an article published in the Monthly Notices of the Royal Astronomical Society.