Among the findings tallying 197 initial planet candidates, scientists have confirmed 104 planets outside our solar system. Among these is a planetary system comprising four promising planets that could be rocky.
The planets, all between 20 and 50 per cent larger than Earth by diameter, are orbiting the M dwarf star K2-72, ere found 181 light years away in the direction of the Aquarius constellation.
The host star is less than half the size of the Sun and less bright.
The planets’ orbital periods range from five and a half to 24 days, and two of them may experience irradiation levels from their star comparable to those on Earth.
“The K2 mission allows us to increase the number of small, red stars by a factor of 20, significantly increasing the number of astronomical ‘movie stars’ that make the best systems for further study,” said lead author Ian Crossfield from University of Arizona’s Lunar and Planetary Laboratory.
Despite their tight orbits — closer than Mercury’s orbit around the Sun — the possibility that life could arise on a planet around such a star cannot be ruled out, he added in a paper published in the Astrophysical Journal Supplement Series.
Both Kepler and its K2 mission discover new planets by measuring the subtle dip in a star’s brightness caused by a planet passing in front of its star.
In the spacecraft’s extended mission in 2013, it lost its ability to precisely stare at its original target area, but a brilliant fix created a second life for the telescope that is proving scientifically fruitful.
After the fix, Kepler started its K2 mission which has provided an ecliptic field of view with greater opportunities for Earth-based observatories in both the northern and southern hemispheres.
These observations represent a natural stepping stone from the K2 mission to NASA’s other upcoming exoplanet missions such as the Transiting Exoplanet Survey Satellite and James Webb Space Telescope.
“This bountiful list of validated exoplanets from the K2 mission highlights the fact that the targeted examination of bright stars and nearby stars along the ecliptic is providing many interesting new planets,” added Steve Howell, project scientist for the K2 mission at NASA’s Ames Research Center in Moffett Field, California.