2021ApJ...922L..43B

In this Letter, we measure the full orbital architecture of the two-planet system around the nearby K0 dwarf 14 Herculis. 14 Her (HD 145675, HIP 79248) is a middle-aged (4.6_–1.3^+3.8 Gyr) K0 star with two eccentric giant planets identified in the literature from radial velocity (RV) variability and long-term trends. Using archival RV data from Keck/HIRES in concert with Gaia-Hipparcos acceleration in the proper motion vector for the star, we have disentangled the mass and inclination of the b planet to 9.1_–1.1^+1.0M_Jup and 32.7_–3.2^+5.3 degrees. Despite only partial phase coverage for the c planet's orbit, we are able to constrain its mass and orbital parameters as well to 6.9_–1.0^+1.7M_Jup and 101_–33⁺³¹ degrees. We find that coplanarity of the b and c orbits is strongly disfavored. Combined with the age of the system and the comparable masses of its planets, this suggests that planet-planet scattering may be responsible for the current configuration of the system.