A new study has revealed 85 potential worlds beyond our solar system that could be cool enough to host life.
The researchers used data from Nasa’s Transitioning Exoplanet Survey Satellite (TESS), which monitors the brightness of stars for signs of planets passing in front of them.
Usually, to confirm the existence of an exoplanet, scientists need to observe at least three such events, called transits, to measure how long it takes for the planet to orbit its star.
But this time, the team focused on systems that only show two transits, which means they have longer orbital periods and therefore cooler temperatures.
The 85 candidate exoplanets range in size from Jupiter to Neptune, and take between 20 and 700 days to complete one orbit around their stars. Most exoplanets detected by TESS have much shorter orbital periods of 3-10 days.
Some of the planets are so far from their stars that they could be in the “habitable zone”, where the temperature is just right for liquid water and life to exist.
However, these are not confirmed exoplanets yet. They still need more observations to verify their nature and characteristics.
Among the 85 candidates, 60 are new discoveries, while 25 have been previously reported by other research groups using different methods.
Faith Hawthorn, PhD researcher at the University of Warwick, said: “We ran an initial algorithm searching for transits on a sample of 1.4 million stars.
After a painstaking vetting process, we whittled this down to just 85 systems that appear to host exoplanets that transit only twice in the dataset.”
Professor Daniel Bayliss, also involved in the research, added: “It’s very exciting to find these planets, and to know that many of them may be in the right temperature zone to sustain life.”
“Encompassing the collaborative spirit of the TESS mission, we have also made our discoveries public so that astronomers across the globe can study these unique exoplanets in more detail. We hope this will drive further research into these fascinating exoplanets.”
Dr Sam Gill, second author of the study, noted: “Detecting exoplanets from just two transits is a clever way to find longer period exoplanets in transit surveys. It allows us to find planets that are much cooler than can be found with traditional transit searches.”
The international collaboration led by Ms Hawthorn at the University of Warwick was published on Wednesday in the Monthly Notices Of The Royal Astronomical Society (MNRAS).