Disk Masses and Dust Evolution of Protoplanetary Disks Around Brown Dwarfs

TL;DR

This study analyzes a large sample of brown dwarf protoplanetary disks across multiple regions to understand their evolution, dust properties, and potential for planet formation, revealing that disks evolve quickly and are generally low in mass.

Contribution

It provides the largest modeled sample of BD disks, comparing their properties across regions and revealing early disk evolution and dust growth.

Findings

Disk mass decreases with age.

Evidence of grain growth and dust settling in all regions.

BD disks generally contain insufficient mass for planet formation.

Abstract

We present the largest sample of brown dwarf (BD) protoplanetary disk spectral energy distributions modeled to date. We compile 49 objects with ALMA observations from four star-forming regions: $\rho$ Ophiuchus, Taurus, Lupus, and Upper Scorpius. Studying multiple regions with various ages enables us to probe disk evolution over time. Specifically, from our models we obtain values for dust grain sizes, dust settling, and disk mass; we compare how each of these parameters vary between the regions. We find that disk mass decreases with age. We also find evidence of disk evolution (i.e., grain growth and significant dust settling) in all four regions, indicating that planet formation and disk evolution may begin to occur at earlier stages. We generally find these disks contain too little mass to form planetary companions, though we cannot rule out that planet formation may have already occurred. Finally, we examine the disk mass -- host mass relationship and find that BD disks are largely consistent with previously-determined relationships for disks around T Tauri stars.