Evidence for Misalignment between Debris Disks and Their Host Stars

Abstract

Abstract We place lower limits on the obliquities between debris disks and their host stars for 31 systems by comparing their disk and stellar inclinations. While previous studies did not find evidence for misalignment, we identify six systems with minimum obliquities falling between ∼30°and 60°, indicating that debris disks can be significantly misaligned with their stars. These high-obliquity systems span a wide range of stellar parameters with spectral types K through A. Previous works have argued that stars with masses below 1.2 M ⊙ (spectral types of ∼F6) have magnetic fields strong enough to realign their rotation axes with the surrounding disk via magnetic warping; given that we observe high obliquities for relatively low-mass stars, magnetic warping alone is likely not responsible for the observed misalignments. Yet, chaotic accretion is expected to result in misalignments of ∼20° at most and cannot explain the larger obliquities found in this work. While it remains unclear how primordial misalignment might occur and what role it plays in determining the spin–orbit alignment of planets, future work expanding this sample is critical toward understanding the mechanisms that shape these high-obliquity systems.