Updated Mutual Inclination Measurement for 14 Her b and c

The mutual inclination ψ between orbits within multi-planetary systems is difficult to measure directly. Through a joint analysis of radial velocities, Hipparcos-Gaia absolute astrometry and relative astrometry of JWST, D. C. Bardalez Gagliuffi et al. recently found two possible values of ψ bc = 3 2 − 15.1 + 13.6 ° and ψ bc = 145 . 0 − 11.1 + 15.8 ° for the nearby, non-transiting planet system, 14 Her. By incorporating additional astrometry from Gaia second data release (DR2), we have further constrained the orbital orientation of 14 Her b, resulting in a definitive and unambiguous mutual inclination of ψ bc = 35 . 3 − 7.3 + 6.8 ° . The unusual misaligned orbital architecture of 14 Her system may serve as a benchmark for dynamical studies.