2025ApJ...995...16Z

Protoplanetary disks are an essential component of the planet formation process. The amount of dust and gas in the disk constrains the number and size of planets that can form in a system. We analyze 178 T Tauri stars, 18 in Serpens and 160 in L1641/L1647, and measure their disk dust masses using spectral energy distribution modeling and multiwavelength data, including 1.3 mm (ALMA band 6) fluxes from the literature. The disk masses calculated in this work are up to ∼2 times higher than those previously reported. We conclude that this is because disks may be partially optically thick at millimeter wavelengths, while most calculations of the disk mass assume that the disk is optically thin at 1.3 mm. We calculate optical depths at 1.3 and 7 mm for a subset of the Serpens and L1641/L1647 disk sample and show that the vast majority of disks become optically thin at longer millimeter wavelengths; thus, observations at 7 mm (i.e., ALMA band 1) are vital to better characterize disk dust masses.