Significant mutual inclinations between the stellar spin and the orbits of both planets in the HAT-P-11 system

Abstract

Planet-star obliquity and planet-planet ]mutual inclination encode a planetary system's dynamical history, but both of their values are hard to measure for misaligned systems with close-in companions. HAT-P-11 is a K4 star with two known planets: a close-in, misaligned super-Neptune with a $\approx$5-day orbit, and an outer super-Jupiter with a $\approx$10-year orbit. In this work we present a joint orbit fit of the HAT-P-11 system with astrometry and S-index corrected RV data. By combining our results with previous constraints on the orientation of the star and the inner planet, we find that all three angular momenta -- those of the star, planet b, and planet c -- are significantly misaligned. We confirm the status of planet c as a super-Jupiter, with $2.68\pm 0.41{\mathrm{M}}_{\mathrm{Jup}}$ at a semimajor axis of $4.10\pm 0.06$AU, and planet b's mass of ${\mathrm{M}}_{\mathrm{b}}\sin {\mathrm{i}}_{\mathrm{b}}=0.074\pm 0.004{\mathrm{M}}_{\mathrm{Jup}}$. We present the posterior probability distribution of obliquity between star A and planet c, and mutual inclination between planet b and planet c.

14 pages, 10 figures, submitted to AJ