The Solar-System-Scale Disk Around AB Aurigae

TL;DR

This study images the dust disk around AB Aurigae at unprecedented resolution, revealing structures like an azimuthal gap and potential signs of planet formation, with implications for understanding disk dynamics.

Contribution

First high-resolution imaging of the inner disk around AB Aurigae, revealing new structures and possible signs of planet formation at about 100 AU.

Findings

Detected an azimuthal gap at 102 AU in the dust disk.

Identified a potential overdensity possibly due to an unseen companion.

Observed a low-significance point source that may indicate a forming planet or dust accumulation.

Abstract

The young star AB Aurigae is surrounded by a complex combination of gas-rich and dust dominated structures. The inner disk which has not been studied previously at sufficient resolution and imaging dynamic range seems to contain very little gas inside a radius of least 130 astronomical units (AU) from the star. Using adaptive-optics coronagraphy and polarimetry we have imaged the dust in an annulus between 43 and 302 AU from the star, a region never seen before. An azimuthal gap in an annulus of dust at a radius of 102 AU, along with a clearing at closer radii inside this annulus, suggests the formation of at least one small body at an orbital distance of about 100 AU. This structure seems consistent with crude models of mean motion resonances, or accumulation of material at two of the Lagrange points relative to the putative object and the star. We also report a low significance detection of a point source in this outer annulus of dust. This source may be an overdensity in the disk due to dust accreting onto an unseen companion. An alternate interpretation suggests that the object's mass is between 5 and 37 times the mass of Jupiter. The results have implications for circumstellar disk dynamics and planet formation.