During the K2 Kepler Mission, 31 stars were discovered that potentially had 36 orbiting planets. After extensive observations using automatic transit analysis, 21 exoplanets, including 17 new discoveries, were confirmed to be real planets, including K2-9b. K2-9b is a M2.5 ± 0.5, 110 ± 12 pc dwarf star with a radius of 2.25 (+0.53-0.96) R⊕ and an orbital period of 18.4498 days. The temperature of K2-9b is estimated to be less than 500 K, which means that the exoplanet receives about the same amount of solar radiation as the Earth. However, according to readings from the ultraviolet space telescope GALEX, UV radiation from its host star is strong enough to affect the planet’s atmosphere and it is improbable that the environment would be hospitable to life. There is still a lot to learn about this exoplanet, especially because it has a low temperature and is around the size of Earth or Neptune.
（Nami Kimura）
References:
Two Small Temperate Planets Transiting Nearby M Dwarfs in K2 Campaigns 0 and 1
Schlieder, Joshua E et al.
Publication:
The Astrophysical Journal, Volume 818, Issue 1, article id. 87, 15 pp. (2016).
Pub Date: February 2016
