High resolution observations reveal dust structure of the protoplanetary disk around HD 163296

Star system: HD 163296 | Distance from the Sun: 331 light years

The protoplanetary disk surrounding the star HD 163296 contains complex structures that provide insight into the birthplace of planets. By analyzing new and archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers have characterized the temperature, density, and size of dust grains within this vast cloud of gas and debris.

To study the disk, the analysis utilized spectral energy distribution fitting, a technique that examines how light is emitted across different wavelengths to infer physical conditions. By comparing these results with VLA (Very Large Array) radio observations and testing various mathematical models of dust, a preferred model—the DSHARP Zubko porous model—was identified to best describe the physical state of the material.

The observations show that the disk is composed of a central region, two distinct rings, and an outer extended area. These features change in appearance depending on the wavelength of light observed, which points to variations in dust depth or size. Additionally, the outer ring is colder than expected, likely because the inner ring casts a shadow that blocks radiation from the central star.

Key findings
- The disk features a central region, two rings at 0.67 and 1.00 arcseconds, and outer extended emission.
- The outer ring is colder than standard models predict, suggesting it is shadowed by the inner ring.
- The preferred dust model indicates that the central disk, both rings, and the outer disk each hold several Earth masses of dust.
- Appearance differences across light frequencies likely result from optical-depth effects or the segregation of dust by size.

Scientific study

Dust characterization of the HD 163296 disk with high-resolution multi-wavelength ALMA observations (external link)