Indications of Rapid Dust Formation in the Inner Region of a Protoplanetary Disk

TL;DR

This study reports a rapid increase in mid-infrared emission from a protoplanetary disk, suggesting quick dust formation likely due to planetesimal collisions near the dust sublimation radius, observed over a two-week period.

Contribution

It provides evidence for rapid, in situ dust formation in a protoplanetary disk, a phenomenon not previously observed on such short timescales.

Findings

Flux increase by a factor of two at ≤10 μm observed in 2 weeks.

Presence of warm, large dust grains near the sublimation radius.

Rapid dust appearance possibly from planetesimal collisions.

Abstract

We report a significant increase in mid-infrared emission $\leq10$ $\mu$m in a transitional disk. The 2024 JWST/MIRI observation of the disk around CVSO 1942 reveals flux increase by a factor of two at $\lambda\leq10$ $\mu$m, compared to the near photospheric flux level observed with Spitzer/IRS in 2005. No significant change in flux at $\gtrsim15$ $\mu$m is detected in the spectra. Comparing the MIRI/MRS spectrum and NEOWISE photometry, we found that this $\leq10$ $\mu$m flux increase occurs on a timescale of 2 weeks and is consistent with the presence of warm (1,400 K), optically thick, large ($\gtrsim1$ $\mu$m) dust grains near the dust sublimation radius. We propose that this rapid dust appearance may indicate in situ dust formation, possibly from planetesimal collisions in the inner disk.