Two transiting planets have been identified orbiting K2 target EPIC 220674823 .
One object is an ultra-short-period planet ( USP ) with a period of just 0.57 days ( 13.7 hours ) , while the other has a period of 13.3 days .
Both planets are small , with the former having a radius of R _ { p 1 } = 1.5 ~ { } R _ { \oplus } and the latter R _ { p 2 } = 2.5 ~ { } R _ { \oplus } .
Follow-up observations , including radial velocity ( with uncertainties of 110 m s ^ { -1 } ) and high-resolution adaptive optics imagery , show no signs of stellar companions .
EPIC 220674823 is the 12th confirmed or validated planetary system in which an ultra-short-period planet ( i.e. , having an orbital period less than 1 day ) is accompanied by at least one additional planet , suggesting that such systems may be common and must be accounted for in models for the formation and evolution of such extreme systems .