Effect of HL Tau’s infalling streamer on inner disk radii remains inconclusive

Ascertain whether the infalling streamer detected in HL Tau by ALMA (Garufi et al. 2022) has a measurable effect at smaller radii by transporting material into the inner disk, and characterize any resulting impact on the inner-disk structure or turbulence to clarify the origin of the observed inner-disk asymmetries.

Background

The paper analyzes a pronounced azimuthal asymmetry in the inner ring of the HL Tau disk observed at 0.45 mm, proposing that it arises from a combination of high optical depth, disk inclination, and relatively large dust scale height. The authors explore toy radiative transfer models that reproduce the asymmetry under different assumptions of dust mass and scale height within 32 au.

They note recent observations of an infalling streamer interacting with HL Tau at larger radii and discuss whether such a feature could influence smaller radii via material flow into the inner disk, potentially affecting turbulence and vertical structure. However, the presence and consequences of any streamer-driven effects at small radii remain unsettled, motivating targeted investigation.