We report the discovery of a compact multi-planet system orbiting the relatively nearby (78 pc) and bright (K = 8.9) K-star, K2-266 (EPIC 248435473). We identify up to six possible planets orbiting K2-266 with estimated periods of Pb = 0.66, P.02 = 6.1, Pc = 7.8, Pd = 14.7, Pe = 19.5, and P.06 = 56.7 days, and radii of R P = 3.3 R ⊕, 0.646 R ⊕, 0.705 R ⊕, 2.93 R ⊕, 2.73 R ⊕, and 0.90 R ⊕, respectively. We are able to confirm the planetary nature of two of these planets (d and e) by analyzing their transit timing variations (md=8.9 +5.7/-3.8 M ⊕ and me = 14.3 +6.4/-5-0 M⊕) confidently validate the planetary nature of two other planets (b and c), and classify the last two as planetary candidates (K2-266.02 and .06). From a simultaneous fit of all six possible planets, we find that K2-266 b's orbit has an inclination of 75 32 while the other five planets have inclinations of 87°–90°. This observed mutual misalignment may indicate that K2-266 b formed differently from the other planets in the system. The brightness of the host star and the relatively large size of the sub-Neptune sized planets d and e make them well-suited for atmospheric characterization efforts with facilities like the Hubble Space Telescope and upcoming James Webb Space Telescope. We also identify an 8.5 day transiting planet candidate orbiting EPIC 248435395, a co-moving companion to K2-266.
- Planetary systems
- Planets and satellites: detection
- stars: individual (K2-266, EPIC 248435395)