The Orbit of Warm Jupiter WASP-106 b is aligned with its Star

TL;DR

This study measures the orbital alignment of the warm Jupiter WASP-106 b, finding it aligned with its star, which supports theories of smooth planetary migration through the protoplanetary disk.

Contribution

First measurement of the projected stellar obliquity for WASP-106 b using Rossiter-McLaughlin observations, confirming aligned orbit and supporting disk migration models.

Findings

Projected stellar obliquity λ = (-1 ± 11)°

Supports quiescent disk migration theory

Orbit is aligned with the star's rotation axis

Abstract

Understanding orbital obliquities, or the misalignment angles between a star's rotation axis and the orbital axis of its planets, is crucial for unraveling the mechanisms of planetary formation and migration. In this study, we present an analysis of Rossiter-McLaughlin (RM) observations of the warm Jupiter exoplanet WASP-106 b. The high-precision radial velocity measurements were made with HARPS and HARPS-N during the transit of this planet. We aim to constrain the orientation of the planet's orbit relative to its host star's rotation axis. The RM observations are analyzed using a code which models the RM anomaly together with the Keplerian orbit given several parameters in combination with a Markov chain Monte Carlo implementation. We measure the projected stellar obliquity in the WASP-106 system for the first time and find $\lambda = (-1 \pm 11)^\circ$, supporting the theory of quiescent migration through the disk.