Hydrogen sulfide detected in the inner disk of HD 163296 reveals sulfur ice sublimation

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

HD 163296 is a young star surrounded by a disk of gas and dust where planets are forming. Using the ALMA telescope, scientists detected compact emission of hydrogen sulfide (H2S) and sulfur oxides in the innermost part of the disk. The emission comes from a region just 3–5 astronomical units from the star, where temperatures are high enough for sulfur-bearing ices to turn into gas.

The observations show that H2S is a major sulfur-containing molecule in this region, with a higher or similar abundance compared to other sulfur oxides. This suggests that as the disk warms up near the star, sulfur locked in ices is released into the gas phase. However, the total amount of volatile sulfur is still uncertain, and some sulfur may be hidden in less-volatile forms like minerals or salts.

These findings help scientists understand how sulfur chemistry evolves in planet-forming disks and how it might affect the composition and habitability of new planets. More observations are needed to fully map the sulfur inventory and its role in planet formation.

Key findings
- Hydrogen sulfide and sulfur oxides detected in the inner disk of HD 163296
- Emission comes from a hot region 3–5 au from the star
- Sulfur-bearing ices are sublimating into gas
- H2S is a major volatile sulfur reservoir in the inner disk
- Some sulfur may be hidden in minerals or salts

Scientific study

Compact Hydrogen Sulfide Emission Indicates Sulfur-bearing Ice Sublimation in the Inner Disk of HD 163296 (external link)