Asteroidscomets

14 Her: A Likely Case of Planet-Planet Scattering

December 2021 • 2021ApJ...922L..43B

Authors • Bardalez Gagliuffi, Daniella C. • Faherty, Jacqueline K. • Li, Yiting • Brandt, Timothy D. • Williams, Lauryn • Brandt, G. Mirek • Gelino, Christopher R.

Abstract • 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 ${9.1}_{-1.1}^{+1.0}$ M 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 ${6.9}_{-1.0}^{+1.7}$ M 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.

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Chris Gelino

Associate Scientist