Figure 1: Artist’s impression of an exoplanet.
Barros et al. (2016) present 172 planetary candidates and 327 eclipsing binary candidates from campaigns 1, 2, 3, 4, 5 and 6 of NASA's K2 mission. Histograms of the orbital periods and transit depths of the planetary and eclipsing binary candidates indicate that a large percentage of candidates have small transit depths. The smallest transit depth is 0.008 percent, which corresponds to a planet with 0.975 times the radius of Earth, assuming its host star is similar in size to the Sun. This planetary candidate is identified as EPIC 211784767b and its orbital period is 3.578 days.
Figure 2: On the left panel: histogram of the orbital periods of the planetary candidates and the eclipsing binary candidates. On the right: histogram of the transit depths of the planetary candidates and the eclipsing binary candidates with transit depths less than 5 percent. Barros et al. (2016)
Reference:
Barros et al. (2016), "New planetary and EB candidates from Campaigns 1-6 of the K2 mission", arXiv:1607.02339 [astro-ph.EP]