Four annular structures in a protostellar disk less than 500,000 years old

Area of Science:

• Astronomy and Astrophysics
• Planetary Science

Background:

• Annular structures (rings and gaps) are common in disks around 1-million-year-old pre-main-sequence stars (Class II objects).
• These structures are often linked to ongoing planet formation, where planetary bodies carve out these features.
• Planet formation might commence even earlier, during the Class I protostellar phase, when stars are still embedded in dense envelopes.

Purpose of the Study:

• To investigate the presence and characteristics of substructures in disks of very young protostars.
• To determine if planet formation processes, indicated by disk substructures, occur earlier than previously thought.

Main Methods:

• Utilized 1.3-millimetre dust emission observations.
• Achieved a high resolution of five astronomical units.
• Focused on the young protostar IRS 63, a Class I source in the Ophiuchus molecular cloud.

Main Results:

• Discovered four annular substructures in the disk of IRS 63, a protostar younger than 500,000 years.
• IRS 63 possesses a relatively large disk (over 50 astronomical units) and is a bright Class I protostar at millimetre wavelengths.
• The observed substructures provide an early opportunity for dust-grain growth, a key step in planet formation.

Conclusions:

• Planet formation processes initiate in the earliest protostellar (Class I) phases.
• The findings suggest that planet formation begins earlier than predicted by current theories.
• The presence of multiple annular substructures in young disks supports early dust growth and potential planet formation.