It's getting hot in here: Refractory solid condensation in a disk around a Class I protostar

Context
The formation of planets such as Earth starts with the recondensation of refractory minerals from hot gas close to a protostar. Recently, crystalline silicates were found to be recondensing from a reservoir of hot SiO gas around Class I protostar HOPS-315 (McClure+25), making it the first detection of this so-called t=0 phase of planetesimal formation. A depletion of iron and silicon in the protostellar jet suggests this t=0 moment may be associated with the formation of the first planetesimals in this disk, similar to the association of refractory inclusions and iron-meteorite parent bodies in the Solar System.

Aims
In this work, we explore whether an even younger Class I protostar with similar properties and system geometries, is engaged in such refractory recondensation as well. A detection of cool gas-phase SiO in absorption above a hot disk midplane would allow us to achieve this goal, thanks to a previous Spitzer detection of crystalline silicates.

Methods
The protostar was observed with the JWST Mid-Infrared Instrument and Near Infrared Spectrograph, showing multiple bands of molecular absorption similar to HOPS-315. We use local thermal equilibrium slab models to measure the temperature, column density, velocity, and radial location of these bands.

Results
The molecular absorption bands of gaseous SiO, H₂O, CO, CO₂, HCN, and C₂H₂ trace a warm molecular inversion layer (~ 300 - 500 K) at mid-altitudes above the hot disk midplane from 0.3 - 19 AU, which is consistently blue-shifted with respect to the system velocity by 33-53 km s^-1. ALMA observations of this protostar kinematically resolve an SiO-rich jet and wind. Unlike for HOPS-315, the infrared SiO velocity for this source matches the velocity of the disk wind.
We find that the young protostar is more carbon-rich than HOPS-315, as we detect multiple additional hydrocarbon species, that were not detected in HOPS-315

Conclusions
We confirm that this protostar, like HOPS-315, is undergoing an epoch analogous to the t=0 moment in the Solar System's planet formation timeline. The detected warm molecular layer traces the base of a disk wind, which carries sublimated silicates and soot from the thermostat region near 2 AU up into the outer disk. We sketch out this proposed mechanism in the figure below.

We find that this source is likely younger than HOPS-315. Therefore, the differences in carbon-rich chemistry between them may be age-related. Its carbon-rich chemistry is likely caused by carbon-rich material being sublimated off the grains in the inner disk and then transported outwards via the detected disk wind. Confirming such a scenario would require higher-resolution (sub)-mm observations of this source. Future identifications of more sources undergoing refractory recondensation will allow us to determine how source age influences the presence and detectability of the t=0 phase.