2025/09/02 by Dingshan Deng, Uma Gorti, Deng, Dingshan +5 · 1 citation
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #High-pressure geophysics and materials #Phase Equilibria and Thermodynamics
paper · pdf · doi:10.48550/arxiv.2509.15487
openalex publication_date 2025/09/02 · openalex created_date 2025/10/01 · openalex updated_date 2026/07/28
Disks around young stars are the birthplaces of planets, and the spatial distribution of their gas and dust masses is critical for understanding where and what types of planets can form. We present self-consistent thermochemical disk models built with DiskMINT, which extends its initial framework to allow for spatially decoupled gas and dust distributions. DiskMINT calculates the gas temperature based on thermal equilibrium with dust grains, solves vertical gas hydrostatic equilibrium, and includes key processes for the CO chemistry, specifically selective photodissociation, and freeze-out with conversion CO/CO2 ice. We apply DiskMINT to study the IM Lup disk, a large massive disk, yet with an inferred CO depletion of up to 100 based on earlier thermochemical models. By fitting the multi-wavelength SED along with the millimeter continuum, \rm C18O radial emission profiles, we find 0.02-0.08 \rm M_\odot for the gas disk mass, which are consistent with the dynamical-based mass within the uncertainties. We further compare the derived surface densities for dust and gas and find that the outer disk is drift-dominated, with a dust-to-gas mass ratio of approximately 0.01-0.02, which is likely insufficient to meet the conditions for the streaming instability to occur. Our results suggest that when interpreted with self-consistent thermochemical models, \rm C18O alone can serve as a reliable tracer of both the total gas mass and its radial distribution. This approach enables gas mass estimates in lower-mass disks, where dynamical constraints are not available, and in fainter systems where rare species like \rm N2H+ are too weak to detect.