Measuring Dust Masses of Protoplanetary Disks in Serpens and L1641/L1647 with ALMA

TL;DR

This study measures dust masses of 178 protoplanetary disks using ALMA data, revealing that previous estimates may be underestimated due to optical thickness, and emphasizes the importance of longer wavelength observations.

Contribution

It provides new disk mass measurements accounting for optical thickness effects and highlights the significance of 7 mm observations for accurate dust mass estimation.

Findings

Disk masses are up to twice as high as previous estimates.

Most disks become optically thin at wavelengths longer than 1.3 mm.

Longer wavelength observations are crucial for accurate mass measurements.

Abstract

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 (SED) 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 $\sim$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.