We report the detection of three small transiting planets around the young K3 dwarf K2-233 ( 2MASS J15215519-2013539 ) from observations during Campaign 15 of the K2 mission .
The star is relatively nearby ( d = 69 pc ) and bright ( V = 10.7 mag , K _ { s } = 8.4 mag ) , making the planetary system an attractive target for radial velocity follow-up and atmospheric characterization with the James Webb Space Telescope .
The inner two planets are hot super-Earths ( R _ { b } = 1.40 \pm 0.06 R _ { \oplus } , R _ { c } = 1.34 \pm 0.08 R _ { \oplus } ) , while the outer planet is a warm sub-Neptune ( R _ { d } = 2.6 \pm 0.1 R _ { \oplus } ) .
We estimate the stellar age to be 360 ^ { +490 } _ { -140 } Myr based on rotation , activity , and kinematic indicators .
The K2-233 system is particularly interesting given recent evidence for inflated radii in planets around similarly-aged stars , a trend potentially related to photo-evaporation , core-cooling , or both mechanisms .