The Coupled Physical Structure of Gas and Dust in the IM Lup Protoplanetary Disk

Abstract

The spatial distribution of gas and solids in protoplanetary disks determines the composition and formation efficiency of planetary systems. A number of disks show starkly different distributions for the gas and small grains compared to millimeter-centimeter sized dust. We present new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the dust continuum, CO, ${}^{13}$CO, and C${}^{18}$O in the IM Lup protoplanetary disk, one of the first systems where this dust-gas dichotomy was clearly seen. The ${}^{12}$CO is detected out to a radius of 970 AU, while the millimeter continuum emission is truncated at just 313 AU. Based upon this data, we have built a comprehensive physical and chemical model for the disk structure, which takes into account the complex, coupled nature of the gas and dust and the interplay between the local and external environment. We constrain the distributions of gas and dust, the gas temperatures, the CO abundances, the CO optical depths, and the incident external radiation field. We find that the reduction/removal of dust from the outer disk exposes this region to higher stellar and external radiation and decreases the rate of freeze-out, allowing CO to remain in the gas out to large radial distances. We estimate a gas-phase CO abundance of $5\%$ of the ISM value and a low external radiation field ($G_0\lesssim 4$). The latter is consistent with that expected from the local stellar population. We additionally find tentative evidence for ring-like continuum substructure, suggestions of isotope-selective photodissociation, and a diffuse gas halo.

19 pages, 16 figures, accepted to ApJ

References in corpus (18)

• Photoevaporation of protoplanetary discs II: evolutionary models and observable properties
• Constraining the X-ray and Cosmic Ray Ionization Chemistry of the TW Hya Protoplanetary Disk: Evidence for a Sub-interstellar Cosmic Ray Rate
• Protoplanetary disk masses from CO isotopologues line emission
• Heat and Dust in Active Layers of Protostellar Disks
• Hydrocarbon emission rings in protoplanetary disks induced by dust evolution
• Mass measurements in protoplanetary disks from hydrogen deuteride
• Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA
• The Impact of Dust Evolution and Photoevaporation on Disk Dispersal
• Hipparcos distances of Ophiuchus and Lupus cloud complexes
• Millimeter imaging of HD 163296: probing the disk structure and kinematics
• Reprocessing of Ices in Turbulent Protoplanetary Disks: Carbon and Nitrogen Chemistry
• ALMA hints at the presence of two companions in the disk around HD 100546
• Investigating grain growth in disks around southern T Tauri stars at millimetre wavelengths
• Exclusion of Cosmic Rays in Protoplanetary Disks. II. Chemical Gradients and Observational Signatures
• Exploring the Origins of Carbon in Terrestrial Worlds
• Searching for Gas-Rich Disks around T Tauri Stars in Lupus
• Diversity in the outcome of dust radial drift in protoplanetary discs
• The disk-bearing young star IM Lup

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