Direct imaging of an asymmetric debris disk in the HD 106906 planetary system

TL;DR

This study presents the first direct imaging of the asymmetric debris disk around HD 106906, revealing its structure, asymmetry, and potential interaction with a nearby planet candidate, offering insights into disk-planet dynamics.

Contribution

First direct scattered light images of HD 106906 debris disk, showing asymmetry and potential planet-disk interaction, with analysis of possible circumplanetary dust.

Findings

Debris disk is near edge-on with a cleared central region.

Outer disk regions are highly asymmetric, resembling a needle morphology.

Planet candidate is likely non-coplanar with the debris disk.

Abstract

We present the first scattered light detections of the HD 106906 debris disk using Gemini/GPI in the infrared and HST/ACS in the optical. HD 106906 is a 13 Myr old F5V star in the Sco-Cen association, with a previously detected planet-mass candidate HD 106906b projected 650 AU from the host star. Our observations reveal a near edge-on debris disk that has a central cleared region with radius $\sim$50 AU, and an outer extent $>$500 AU. The HST data show the outer regions are highly asymmetric, resembling the ''needle'' morphology seen for the HD 15115 debris disk. The planet candidate is oriented $\sim$21$\deg$ away from the position angle of the primary's debris disk, strongly suggesting non-coplanarity with the system. We hypothesize that HD 106906b could be dynamically involved in the perturbation of the primary's disk, and investigate whether or not there is evidence for a circumplanetary dust disk or cloud that is either primordial or captured from the primary. We show that both the existing optical properties and near-infrared colors of HD 106906b are weakly consistent with this possibility, motivating future work to test for the observational signatures of dust surrounding the planet.