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Context. Observations of edge-on disks are an important tool for constraining general protoplanetary disk properties that cannot be determined in any other way. However, most radiative transfer models cannot simultaneously reproduce the spectral energy distributions (SEDs) and resolved scattered light and submillimeter observations of these systems because the geometry and dust properties are different at different wavelengths. Aims. We simultaneously constrain the geometry of the edge-on protoplanetary disk HH 48 NE and the characteristics of the host star. HH 48 NE is part of the JWST early-release science program Ice Age. This work serves as a stepping stone toward a better understanding of the physical structure of the disk and of the icy chemistry in this particular source. This type of modeling lays the groundwork for studying other edge-on sources that are to be observed with the JWST. Methods. We fit a parameterized dust model to HH 48 NE by coupling the radiative transfer code RADMC-3D and a Markov chain Monte Carlo framework. The dust structure was fit independently to a compiled SED, a scattered light image at 0.8 µm, and an ALMA dust continuum observation at 890 µm. Results. We find that 90% of the dust mass in HH 48 NE is settled to the disk midplane. This is less than in average disks. The atmospheric layers of the disk also exclusively contain large grains (0.3–10 µm). The exclusion of small grains in the upper atmosphere likely has important consequences for the chemistry because high-energy photons can penetrate very deeply. The addition of a relatively large cavity (~50 au in radius) is necessary to explain the strong mid-infrared emission and to fit the scattered light and continuum observations simultaneously. [ABSTRACT FROM AUTHOR]

Context. The abundance and distribution of ice in protoplanetary disks is critical for an understanding of the link between the composition of circumstellar matter and the composition of exoplanets. Edge-on protoplanetary disks are a useful tool for constraining this ice composition and its location in the disk because the spectral signatures of the ice can be observed in absorption against the continuum emission that arises from the warmer regions in the central disk. Aims. The aim of this work is to model ice absorption features in protoplanetary disks and to determine how well the abundance of the main ice species throughout the disk can be determined within the uncertainty of the physical parameter space. The edge-on proto-planetary disk around HH 48 NE, a target of the James Webb Space Telescope Early Release program Ice Age, is used as a reference system. Methods. We used the full anisotropic scattering capabilities of the radiative transfer code RADMC-3D to ray-trace the mid-infrared continuum. Using a constant parameterized ice abundance, we added ice opacities to the dust opacity in regions in which the disk was cold enough for the main carbon, oxygen, and nitrogen carriers to freeze out. Results. The global abundance relative to the dust content of the main ice carriers in HH 48 NE can be determined within a factor of 3 when the uncertainty of the physical parameters is taken into account. Ice features in protoplanetary disks can be saturated at an optical depth of ≲1 due to local saturation. Ices are observed at various heights in the disk model, but in this model, spatial information is lost for features at wavelengths >7 µm when observing with James Webb Space Telescope because the angular resolution decreases towards longer wavelengths. Spatially observed ice optical depths cannot be directly related to column densities, as would be the case for direct absorption against a bright continuum source, because of radiative transfer effects. Vertical snowlines will not be a clear transition because the height of the snow surface increases radially, but their location may be constrained from observations using radiative transfer modeling. Radial snowlines are not really accessible. Not only the ice abundance, but also the inclination, the settling, the grain size distribution, and the disk mass have a strong impact on the observed ice absorption features in disks. Relative changes in the ice abundance can only be inferred from observations if the source structure is well constrained. [ABSTRACT FROM AUTHOR]

Context. The composition of planets may be largely determined by the chemical processing and accretion of icy pebbles in protoplanetary disks. Recent observations of protoplanetary disks hint at wide-spread depletion of gaseous carbon. The missing volatile carbon is likely frozen in CO and/or CO2 ice on grains and locked into the disk through pebble trapping in pressure bumps or planetesimals. Aims. We aim to measure the total elemental C/H ratio in the outer region of seven disks, four of which have been previously shown to be depleted of carbon gas interior to 0.1 AU through near-infrared spectroscopy. Methods. We present the results of the first successful Atacama Compact Array (ACA) [C I] J = 1−0 mini-survey of seven protoplanetary disks. Using tailored azimuthally symmetric Dust And LInes thermo-chemical disk models, supported by the [C I] J = 1−0 and resolved CO isotopologue data, we determine the system-averaged elemental volatile carbon abundance in the outer disk of three sources. Results. Six out of the seven sources are detected in [C I] J = 1−0 with ACA, four of which show a distinct disk component. Based on the modeling we find severe cold gaseous carbon depletion by a factor of 157+17-15 in the outer disk of DL Tau and moderate depletion in the outer disks of DR Tau and DO Tau, by factors of 5+2-1 and 17+3-2, respectively. The carbon abundance is in general expected to be higher in the inner disk if carbon-rich ices drift on large grains toward the star. Combining the outer and inner disk carbon abundances, we demonstrate definitive evidence for radial drift in the disk of DL Tau, where the existence of multiple dust rings points to either short-lived or leaky dust traps. We find dust locking in the compact, smooth disks of DO Tau and DR Tau, which hints at unresolved dust substructure. Comparing our results with the inner and outer disk carbon depletion around stars of different ages and luminosities, we identify an observational evolutionary trend in gaseous carbon depletion that is consistent with dynamical models of CO depletion processes. Conclusions. The transport efficiency of solids in protoplanetary disks can significantly differ from what we expect based on the current resolved substructure in the continuum observations. This has important implications for our understanding of the impact of radial drift and pebble accretion on planetary compositions. [ABSTRACT FROM AUTHOR]

Context. Volatile molecules are critical to terrestrial planetary habitability, yet they are difficult to observe directly where planets form at the midplanes of protoplanetary disks. It is unclear whether the inner ∼1 AU of disks are volatile-poor or if this region is resupplied with ice-rich dust from colder disk regions. Dust traps at radial pressure maxima bounding disk gaps can cut off the inner disk from these types of volatile reservoirs. However, the trap retention efficiency and atomic composition of trapped dust have not been measured. Aims. We present a new technique to measure the absolute atomic abundances in the gas accreting onto T Tauri stars and infer the bulk atomic composition and distribution of midplane solids that have been retained in the disk around the young star TW Hya. Methods. We identify near-infrared atomic line emission from gas-phase material inside the dust sublimation rim of TW Hya. Gaussian decomposition of the strongest H Paschen lines isolates the inner disk hydrogen emission. We measure several key elemental abundances, relative to hydrogen, using a chemical photoionization model and infer dust retention in the disk. With a 1D transport model, we determine approximate radial locations and retention efficiencies of dust traps for different elements. Results. Volatile and refractory elements are depleted from TW Hya's hot gas by factors of ∼102 and up to 105, respectively. The abundances of the trapped solids are consistent with a combination of primitive Solar System bodies. Dust traps beyond the CO and N2 snowline cumulatively sequester 96% of the total dust flux, while the trap at 2 AU, near the H2O snowline, retains 3%. The high depletions of Si, Mg, and Ca are explained by a third trap at 0.3 AU with >95% dust retention. Conclusion. TW Hya sports a significant volatile reservoir rich in C- and N-ices in its outer submillimeter ring structure. However, unless the inner disk was enhanced in C by earlier radial transport, typical C destruction mechanisms and the lack of a C resupply should leave the terrestrial planet-forming region of TW Hya "dry" and carbon-poor. Any planets that form within the silicate dust trap at 0.3 AU could resemble Earth in terms of the degree of their volatile depletion. [ABSTRACT FROM AUTHOR]