On the alignment of debris disks and their host stars' rotation axis -implications for spin-orbit misalignment in exoplanetary systems

TL;DR

This study investigates whether debris disks around stars are aligned with the stars' rotation axes, finding no evidence of misalignment, which has implications for understanding the origins of spin-orbit misalignments in exoplanet systems.

Contribution

The paper provides observational evidence that debris disks are aligned with their host stars' rotation axes, challenging assumptions about star-disk misalignment affecting exoplanet spin-orbit angles.

Findings

Debris disks are generally aligned with stellar rotation axes.

No significant misalignment found between debris disks and host stars.

Results impact theories of planet migration and spin-orbit misalignment.

Abstract

It has been widely thought that measuring the misalignment angle between the orbital plane of a transiting exoplanet and the spin of its host star was a good discriminator between different migration processes for hot-Jupiters. Specifically, well-aligned hot-Jupiter systems (as measured by the Rossiter-McLaughlin effect) were thought to have formed via migration through interaction with a viscous disk, while misaligned systems were thought to have undergone a more violent dynamical history. These conclusions were based on the assumption that the planet-forming disk was well-aligned with the host star. Recent work by a number of authors has challenged this assumption by proposing mechanisms that act to drive the star-disk interaction out of alignment during the pre-main sequence phase. We have estimated the stellar rotation axis of a sample of stars which host spatially resolved debris disks. Comparison of our derived stellar rotation axis inclination angles with the geometrically measured debris-disk inclinations shows no evidence for a misalignment between the two.