Meridional flows in the disk around a young star

Area of Science:

• * Astronomy and Astrophysics
• * Planetary Science

Background:

• * Protoplanetary disks exhibit substructures like rings and gaps, often attributed to forming planets or hydrodynamic instabilities.
• * Gas velocity structure is crucial for understanding disk evolution, material transport, and angular momentum removal during planet formation.

Purpose of the Study:

• * To investigate the gas velocity structure in the upper layers of the protoplanetary disk around the young star HD 163296.
• * To determine if observed disk substructures correlate with specific gas flow patterns.

Main Methods:

• * Radial profiles of three gas velocity components were measured using 12CO emission.
• * Observations focused on the upper layers of the HD 163296 protoplanetary disk.

Main Results:

• * Substantial gas flows from the disk surface towards the midplane were detected at the radial locations of known gaps.
• * These flows closely resemble predicted meridional flows associated with early planet formation.
• * A persistent radial outflow was observed at the outer edge of the disk, potentially indicating the base of a stellar wind.

Conclusions:

• * The observed gas flows support the hypothesis that embedded planets sculpt disk gaps and drive material towards the midplane.
• * These findings provide observational evidence for theoretical models of planet formation and disk evolution.
• * The study highlights the role of gas dynamics in planet formation and angular momentum transport within protoplanetary disks.