Nearly 80 possible exoplanets - planets beyond our Solar System - have been discovered in a survey of 50,000 stars by the K2 mission, a follow-up mission of the Kepler Space Telescope.


The discoveries were made in record time and the mission is being taken as a ‘dry run’ for the new Transiting Exoplanet Survey Satellite (TESS), which launched in April 2018.

One of the standout candidates is a likely exoplanet orbiting star HD 73344. If confirmed, it would be the brightest planet host ever discovered by the K2 mission.

Astronomers estimate this exoplanet to be about 2.5 times the size of Earth but 10 times as massive.

It is likely to have a surface temperature around 1,200 - 1,300°C and lies about 114 lightyears from Earth.

“We think it would probably be more like a smaller, hotter version of Uranus or Neptune,” says Ian Crossfield, an assistant professor of physics at the Massachusetts Institute of Technology, who co-led the study with graduate student Liang Yu.

The study used existing graphs of light intensity called ‘light curves’ from each of the 50,000 stars that were observed by K2 in recent campaigns.

Computer algorithms whittled the stars down to about 1,000 of interest, and the team then looked for dips in the stars’ brightness, as this can be an indication of planets in orbit.

“When the TESS data come down, there’ll be a few months before all of the stars that TESS looked at for that month ‘set’ for the year,” says Crossfield.

“If we get candidates out quickly to the community, everyone can start immediately observing systems discovered by TESS, and doing a lot of great planetary science.

So this [analysis] was really a dress rehearsal for TESS.”


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Iain Todd BBC Sky at Night Magazine
Iain ToddScience journalist

Iain Todd is BBC Sky at Night Magazine's Content Editor. He fell in love with the night sky when he caught his first glimpse of Orion, aged 10.