AB Aurigae’s disk shows complex dynamics and accretion activity

Researchers observed the protoplanetary disk around the young star AB Aurigae using near-infrared polarized imaging and H-alpha observations over several years. Their study reveals that while most of the disk follows Keplerian rotation, the inner regions (within about 60 astronomical units) show significant deviations, including sub-Keplerian motion. Two bright spiral arms inside the disk’s millimeter cavity display different dynamic behaviors, possibly linked to planet candidates within the disk.

The team also found that some compact sources (labeled f1, f2, and f3) have orbits highly inclined relative to the disk plane, suggesting complex interactions. Variability in disk shadows points to optically thick regions close to the star. H-alpha imaging allowed the researchers to estimate mass accretion rates for these features. For example, the feature f1 could correspond to a mass of 5–20 Jupiter masses if accretion is steady, but AB Aur b itself was not detected in H-alpha.

These findings suggest that the disk’s dynamics are influenced by multiple protoplanets, some possibly on inclined orbits, and that accretion processes are ongoing in the system.

Key findings
- AB Aurigae’s disk mostly rotates in a Keplerian manner, but the inner disk shows sub-Keplerian motion.
- Bright spirals and compact sources have complex, possibly planet-driven dynamics.
- Some compact sources orbit at high inclinations to the disk plane.
- Shadows in the disk are caused by optically thick regions within 60 au.
- Accretion rates suggest some features could be massive protoplanets.

Scientific study

Destructuring the disk of AB Aurigae: Dynamics and accretion (external link)