arXiv subjects

Inga Kamp

Publications and source records attributed to Inga Kamp.

At least 19 recordsLinked to original sources

arXiv2026

XUE. ProDiMo models of internally and externally irradiated planet-forming disks around 0.3-4.0 solar mass stars (The IRIS project I)

Most stars and planets form in massive star-forming regions, where disks are exposed to external far-ultraviolet (FUV) radiation from nearby O- and B-type stars. The combined effects of stellar irradiation and external FUV fields on terrestrial planet-forming regions (< 10 au) across stellar masses remain unclear. We investigate how internal UV and X-ray irradiation and external FUV fields affect mid-infrared (mid-IR) gas emission and the atmospheric carbon-to-oxygen (C/O) ratios inferred in T Tauri and Herbig Ae/Be disks. We compute disk structures with ProDiMo and synthetic spectra with FLiTs, convolved to a representative JWST/MIRI-MRS resolution (R$\sim$2680). (1) We present the Internal and external irRadIation of diSks (IRIS) grid: four model sets spanning stellar masses of 0.3-4.0 solar masses, including stellar X-ray flares and an external FUV field of 1e4 G0 (Habing units). (2) We predict increasing flux densities with stellar mass for key atomic and molecular mid-IR tracers. (3) External FUV irradiation enhances CH3+ and H2 emission, whereas FUV-induced disk truncation yields inner disk chemistry resembling that of disks irradiated only by their host stars. (4) Mid-IR H2O, CO2, and C2H2 line ratios imply carbon-rich compositions (C/O$\sim$1-10) in the warm emitting layers of T Tauri and Herbig Ae/Be disks, primarily reflecting stellar irradiation, with little sensitivity to external FUV irradiation. The IRIS grid provides a flexible framework for interpreting JWST and future Extremely Large Telescope (ELT) infrared disk observations across a broad range of stellar properties and irradiation conditions. Future models should include FUV-driven photoevaporative winds, X-ray radiative transfer, and time-dependent X-ray irradiation.

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arXiv2026

MINDS: Complementary inclinations in the binary system HK Tau reveal gas- and ice-phase chemistry

[Abridged] HK Tau is a roughly equal mass pre-main sequence binary system consisting of a low-inclination primary (57 deg) and an edge-on (83 deg) secondary. We present JWST/MIRI observations targeting both sources, taken as part of the JWST GTO program MINDS. The spectra reveal a line-rich, CO2-dominated primary and a line-poor secondary; this evidence, albeit in line with the evolutionary-motivated trend uncovered by recent observations of binaries at MIRI wavelengths, is likely due to the different configuration of the two sources. Indeed, thermochemical disc models coupled with radiative transfer show that, at inclinations comparable to that of HK Tau B, only ionised atomic lines are expected to remain visible in the spectra. While blocking molecular emission lines, however, the edge-on configuration allows ice absorption bands to be visible against the continuum; in this framework, the HK Tau system provides an unprecedented opportunity to have a simultaneous view of the solid and gaseous component of a pair of coeval protoplanetary discs, thanks to the complementary inclination of the two sources. We detect water ice at 6.2 and 13.6um, CO2 ice at 15.2um, and NH4+ ice at 6.85um in the spectrum of HK Tau B; an additional absorption band between 8.3 and 9um is compatible with both silicate stretching and C-H bending. Neither of the two sources show signs of PAHs. Extended H2 emission is present around both discs, although much more elongated in HK Tau B. The distinctive 'X' shape centred in B, combined with the intensity, morphology, and spectral characteristics of the ionised atomic lines [Ar II], [Ne II], and [Ne III] suggests a low-velocity wind origin with a wide (~ 70 deg) semi-opening angle. The lower forbidden line fluxes and smaller extent of the H2 emission around A imply that, if a wind is launched from the primary as well, it is too cold or dense to be ionised.

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arXiv2026

Geophysical and atmospheric implications of $f$O$_{2}$-dependent melting on rocky exoplanets

The geochemical evolution of long-lived magma oceans is strongly regulated by volatile exchange between the molten mantle and the atmosphere. For planets inside the runaway-greenhouse limit, this coupled evolution can persist for billions of years. However, most existing studies assume Earth-like (oxidized) conditions and neglect the influence of redox state on melt thermodynamics and volatile release. We quantified how experimentally derived, oxygen-fugacity-dependent melting curves implemented within the coupled interior-atmosphere framework PROTEUS propagate into the thermal structure, melt fraction, and rheological evolution of rocky exoplanet interiors, applying this to the short-period super-Earth GJ 1132 b. We found strongly non-linear thermal responses to variations in melting curves. In volatile-poor systems, reduced melting curves promote earlier deep-mantle crystallisation relative to oxidised and Earth-like cases, favouring late-stage surface magma oceans sustained by greenhouse warming, while oxidized melting curves maintain higher melt fractions and a vertically extended magma ocean. Reduced mantles produce massive H$_2$-CO-rich atmospheres; oxidized mantles favour thinner H$_2$O-CO$_2$ envelopes. In volatile-rich systems, the interior reaches radiative equilibrium at high melt fractions, sustaining a steady-state global magma ocean in which melting curve variations do not significantly influence solidification timing. This indicates a hierarchical control: volatile inventory and surface oxygen fugacity act as the primary regulators of thermal state, while oxygen-fugacity-dependent melting relations provide a secondary modulation. These contrasting regimes produce distinct atmospheric compositions and formation timescales, offering testable spectral predictions for close-in rocky exoplanets evaluable with forthcoming JWST observations.

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arXiv2026

Chemistry and IR emission of acetylene in planet-forming regions of T Tauri disks. Impact of elemental abundances and dust properties

(Abridged) We aim to explore the parameters that influence the mid-infrared emission of C$_2$H$_2$ and H$_2$O, and if the spread observed in $F\rm{_{C_2H_2}}$/$F\rm{_{H_2O}}$ is tracing a variation of the C/O ratio. Our work is based on the DALI 2D thermochemical model to predict spectra readily comparable to JWST/MIRI observations. To robustly model organics in inner disks, several improvements have been made: (1) carbon chemistry adapted for warm environments, (2) updated UV shielding treatment, and (3) mutual line overlap in the raytracing. We are able to reproduce the observed C$_2$H$_2$ fluxes of T Tauri disks with a solar C/O ratio. Acetylene abundance is primarily set by a balance between formation initiated by CO dissociation by X-rays and destruction of carbon chains by atomic oxygen, the latter being generated by X-ray-induced destruction of H$_2$O and CO. The water UV shielding and hot temperatures of the inner disk also favor acetylene formation, as they prevent the destruction of carbon chains and allow overcoming activation barriers of reactions with H$_2$. C$_2$H$_2$ and H$_2$O emissions are not only sensitive to the C/O ratio but also to the total O/H elemental abundance, supporting recent claims. In particular, we find that enhanced O/H reduces acetylene emission due to an excess of atomic oxygen. $F_{\rm{C_2H_2}}$/$F_{\rm{H_2O}}$ is thus a promising tracer of the elemental composition of inner disks. Still, the dust size distribution also plays a key role in this line flux ratio. We find that increasing the abundance of small grains relative to large grains favors C$_2$H$_2$ flux over H$_2$O flux. Grain depletion does not affect the line flux ratio as previously suggested by observational works. A preliminary comparison with published JWST observations indicates a gas-phase C/O ratio below unity and suggests that enhanced O/H ratios may be common in T Tauri disks.

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arXiv2026

MINDS: Intertwined evolution of dust and gas in large planet-forming disks. A diversity driven by halted pebble drift?

(Abridged) We aim to investigate the inner regions of large and massive disks orbiting T Tauri stars, thought to be progenitors of systems with wide-orbit planets and possible cases of halted pebble drift. We analyze the MIRI spectra of three disks from the MINDS program: V1094 Sco, DL Tau, and IM Lup. The spectra reveal a striking diversity. V1094 Sco and DL Tau exhibit the highest C$_2$H$_2$/H$_2$O flux ratio in the MINDS sample of T Tauri disks. In V1094 Sco, even cold C$_4$H$_2$ is seen. In contrast, the IM Lup spectrum is dominated by O-bearing species. No one-to-one correspondence is found between the gas in the outer disk, as traced by the C$_2$H/C$^{18}$O flux ratio, and that of the inner disk as traced by the C$_2$H$_2$/H$_2$O flux ratio. To explain these results, we propose a scenario based on a toy model of halted pebble drift. We show that a volatile C/O ratio close to unity and low C and O abundances in inner disks arise only if: (1) ~95$\%$ of the icy grains are blocked in the outer disk, (2) the outer disk is chemically evolved, and (3) the gas in the outer disk has had time to reach the inner disk. DL Tau and perhaps V1094 Sco would be the rare examples for which all these conditions are met. Therefore, a high C$_2$H$_2$/H$_2$O flux ratio in pebble-rich disks would have a different origin than proposed for very-low mass stars, for which fast drift of O-rich pebbles would eventually leave a C-rich inner disk. We also show for the first time that the disks with high C$_2$H$_2$/H$_2$O flux ratio exhibit a prominent silica dust component, a result found in four disks published so far (V1094 Sco, DL Tau, CY Tau, DoAr 33). We propose that the reformation of dust at the sublimation front of silicates in a gas with super-solar (but below unity) C/O ratio leads to a silica stoichiometry (SiO$_2$). In turn, silica is a promising diagnostic of the C/O ratio in the inner disks.

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arXiv2026

Detecting nitrogen-carriers in the inner regions of protoplanetary disks

Nitrogen is a key element for building habitable worlds, yet only a small fraction of the available N-budget of planet-forming disks has been detected. In particular, the lack of any IR NH$_3$ detection is striking, as this molecule is predicted to be rather abundant in the warm, inner regions of protoplanetary disks, and therefore potentially readily incorporated into (giant) planets' atmospheres. We present a combined modeling and observational study of N-bearing molecules in planet-forming disks, using detailed thermo-chemical disk models that investigate the sensitivity of N-containing molecules to the bulk elemental composition of the disk. Our models predict a strong increase in HCN flux with high C/H, and conversely a strong increase in flux from NO when O/H is high. The flux from NH$_3$ is not very sensitive to O/H, but does decrease at high C/H due to competition with HCN. However, the absolute NH$_3$ flux predicted by our model is not large enough to be detected with JWST-MIRI, even when N/H is enhanced by an order of magnitude. The flux from NO, on the other hand, is potentially detectable, and could therefore provide further insights into the N-budget of the inner disk. Using a cross-correlation technique, we search for NH$_3$ and NO detections in three disks, GW Lup, Sz 98, and V1094 Sco. We do not find any NH$_3$ detections, and only one tentative NO detection in V1094 Sco, though this needs further study to be confirmed. Additionally, we demonstrate that future facilities in the FIR may provide a better opportunity to detect NH$_3$ and thereby draw a comparison to the NH$_3$ budget known to be present in interstellar ices.

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arXiv2026

JWST Edge-on Disk Ice (JEDIce): Program overview and ice survey results

The icy material within protoplanetary disks plays a central role in planet formation, yet remains poorly characterized by observations. We present 1.6-28$\mu$m spectra of five disks obtained as part of the JWST Edge-on Disk Ice (JEDIce) program, representing the largest survey of disk ices to date. The major ice species H$_2$O, CO$_2$, and CO are detected towards all disks, and exhibit a wide range of absolute optical depths and optical depth ratios across the sample. This is suggestive of a range of ice abundances and compositions, but quantitative constraints will require radiative transfer modeling. All disks exhibit ice features across the entire spatial region where the IR continuum is detected; vertically elevated ice grains therefore seem to be ubiquitous in disks. The CO ice is consistently dominated by apolar CO:CO$_2$ mixtures, implying that the disk ice compositions are neither completely reset nor pristinely inherited from the protostellar stage. The presence of these mixtures also suggests that entrapment may be important in shaping the spatial distribution of CO within the disks. Small molecules commonly seen in protostellar ices (CH$_4$, CH$_3$OH, NH$_3$) are generally not detected in our sample, though tracers of ammonium salts (OCN$^-$ and the 6.85 $\mu$m band) are common, potentially reflecting an evolution towards comet-like ice compositions. The spectra also contain a wealth of information about the micron-sized dust, atomic and molecular gas, and PAH content, which together with the ice constraints will provide a comprehensive picture of the chemical, physical, and dynamical state of these systems.

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arXiv2026

Molecular diagnostics for the mid-infrared emission of planet-forming disks. Carbon and oxygen elemental abundances

Mid-infrared observations of planet-forming disks reveal a wide diversity in molecular spectra. Carbon and oxygen abundances play a central role in setting the chemical environment of the inner disk and the spectral appearance. We aim to systematically explore how variations in elemental carbon and oxygen abundances affect the mid-infrared spectra of planet-forming disks, and to identify robust mid-infrared molecular diagnostics of C/H, O/H, and the C/O ratio. Using the thermochemical disk code ProDiMo and the line radiative transfer code FLiTs, we construct a grid of 25 models with varying carbon and oxygen abundances, covering a broad range of C/O ratios. We analyze the resulting mid-infrared molecular emission, including species such as $\rm H_2O$, $\rm CO$, $\rm CO_2$, $\rm C_2H_2$, $\rm OH$. We find that the mid-infrared molecular spectra are highly sensitive not only to the C/O ratio, but also to the absolute abundances of carbon and oxygen. Despite the same disk structure and C/O ratios, molecular fluxes (e.g., $\rm C_2H_2$, $\rm CO_2$) vary by more than an order of magnitude. This variation stems from the differences in excitation conditions and emitting regions caused by the elemental abundances of oxygen and carbon. We identify diagnostic molecular flux ratios - such as $\rm CO_2$/$\rm H_2O$ and $\rm H_2O$/$\rm C_2H_2$ - that can serve as tracers of C/H and O/H respectively. By combining these diagnostics, we demonstrate a method to infer the underlying C/O ratio. Our model grid provides a framework for interpreting mid-infrared molecular emission from disks, allowing estimates of elemental abundances if the disk properties and structure are known. Comparisons with recent JWST observations suggest that a variety in C and O abundances is seen in a sample of T Tauri disks, possibly shaped by disk transport processes and the presence of gaps.

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arXiv2025

MINDS: The molecule-rich disc of the Herbig star HD 35929 revealed with JWST/MIRI

Our knowledge of the chemical composition of the gas in the inner disc of intermediate-mass young stars is limited, due to the lack of suitable instrumentation. The launch of JWST has provided a significant improvement in our ability to probe gas in these inner discs. We analyse the gas composition and emitting conditions of the disc around HD 35929, a young intermediate-mass Herbig star, using MIRI/MRS data. Our goal is to constrain the chemistry and kinematics of the gas phase molecules detected in the inner disc. We use iSLAT to examine the observed molecular lines and DuCKLiNG to detect, fit, and analyse the molecular emission. We find gas phase H2O, CO, CO2, and OH in the disc, as well as HI recombination lines. Surprisingly, we also detect gas phase SiO in the fundamental v=1-0 vibrational band. We derive column densities and temperature ranges of the detected species, arising from the inner ~0.2 au, hinting towards a compact and very warm disc. The molecular column densities are much higher than found in lower mass T Tauri discs. In general, the molecular composition is consistent with an O-rich gas from which silicate-rich solids condense and the strong gas phase molecular line emission suggests a low dust opacity. The unexpected detection of gas phase SiO at the source velocity points to an incomplete condensation of rock forming elements in the disc, suggesting chemical disequilibrium and/or an underestimate of the gas kinetic temperature.

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arXiv2025

Detectability of resolved hydrogen lines from the accretion shock at gas giants and their CPDs

Fewer gas giants have been caught in their accretion phase than mature ones are known. Extremely Large Telescope (ELT) instruments will have a higher sensitivity and a smaller inner working angle than tools up to now, which should increase search yields. We examine what METIS, the first-generation ELT spectrograph with R=1e5, can reveal about accreting gas giants. We focus on the accessible hydrogen recombination lines, mainly Brackett alpha and Pfund-series lines. Our approach is general but we take PDS70b as a fiducial case. It is similar to WISPIT2b. To calculate high-resolution line profiles, we combine a semianalytical multi-D description of the flow onto an accreting planet and its circumplanetary disc (CPD) with local non-LTE shock-emission models. We assume the limiting scenario of no extinction, appropriate for gas giants in gaps, and negligible contribution from magnetospheric accretion. We use simulated detector sensitivities to compute needed observing times. Both the planet- and the CPD-surface shocks contribute to the line, which has a Gaussian core but wider, asymmetrical wings. The line is much narrower than the free-fall velocity, and in fact has a nearly constant FWHM=30--40 km/s at low densities. For our fiducial accretion rate onto PDS70b, the Br-a line peak excess is as strong as the photospheric continuum, modulated mostly by H2O features. At Br-a, already the continuum of PDS 70 b yields a per-bin S/N=12 in 4h. With ProDiMo, we estimate the CPD not to hinder the detection of the line emission. The peak excess should require only 10 min to reach S/N=3. For pure shock emission, the line shape is barely sensitive to the planetary or system parameters. A complex profile would indicate that magnetospheric accretion contributes significantly. The high spectral resolution of METIS will help reveal line shapes even of faint accretors with great fidelity.

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arXiv2025

MINDS: The very low-mass star and brown dwarf sample II. Probing disk settling, dust properties, and dust-gas interplay with JWST/MIRI

Disks around very low-mass stars (VLMS) provide environments for the formation of Earth-like planets. Mid-infrared observations have revealed that these disks exhibit weak silicate features and strong hydrocarbon emissions. This study characterizes the dust properties and geometrical structures of VLMS and brown dwarf (BD) disks, observed by the James Webb Space Telescope (JWST)/Mid-Infrared Instrument (MIRI), and connects these to gas column density and potential evolutionary stages. We analyze mid-infrared spectra of ten VLMS and BD disks as a part of the MIRI mid-Infrared Disk Survey (MINDS) program. Spectral slopes and silicate band strengths are compared with hydrocarbon emission line ratios, which probe the gas column density. Moreover, the Dust Continuum Kit with Line emission from Gas is used to quantify grain sizes, dust compositions, and crystallinity in the disk surface. The disks are classified into less, more, and fully settled geometries based on their mid-infrared spectral slopes and silicate band strengths. Less-settled disks show a relatively strong silicate band, high spectral slopes, and low crystallinity, and are dominated by 5 $\mu$m-sized grains. More-settled disks have weaker silicate band, low spectral slope, enhanced crystallinity, and higher mass fractions of smaller grains. Fully-settled disks exhibit little or no silicate emission and negative spectral slopes. An overall trend of increasing gas column density with decreasing spectral slope suggests that more molecular gas is exposed when the dust opacity decreases due to dust settling. Our findings may reflect possible evolutionary pathways with dust settling and thermal processing or may point to inner-disk clearing or a collisional cascade. These results highlight the need for broader samples to understand the link between dust and gas appearance in regions where Earth-like planets form.

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arXiv2025

MINDS. Strong oxygen depletion in the inner regions of a very low-mass star disk?

JWST is discovering a plethora of species in planet-forming disks around very low-mass stars such as C2H2, C6H6, C4H2, CH3 etc. The column densities of these species retrieved from 0D slab models are very large, e.g. of the order of $10^{20}$\,cm$^{-2}$. This is indicating a carbon-dominated chemistry in a gas with a high C/O ratio. The disk around 2MASS-J1605321-1993159 (M4.5) is one such source showing a molecular pseudo-continuum of C2H2. Still two oxygen-bearing molecules, CO and CO2 are also detected in this source. We aim to take the next step beyond 0D slab models to interpret the spectrum. We examine whether 2D thermo-chemical disk models can produce the large inferred column densities of \ce{C2H2} in the inner regions of the disk and produce a pseudo-continuum in the mid-IR spectrum. We also want to constrain whether depletion of oxygen or enrichment of carbon is causing the high C/O ratio triggering a carbon-dominated chemistry. We utilize the radiative thermo-chemical disk model P{\tiny RO}D{\tiny I}M{\tiny O} to identify a disk structure which is capable of producing the observed molecular emission of species such as CO, CO2, C2H2, and H2O simultaneously. The spectrum is generated using the fast line tracer FLiTs. We derive the gas temperature $\langle T \rangle$, column density $\langle$ log$_{\rm {10}} N\rangle$ and the emitting area $\langle r_{\rm{1}} - r_{\rm{2}} \rangle$ for these molecules from the 2D disk model and compare them to the parameters retrieved originally from 0D slab models. We use the different effect that changing the O or C abundance has on CO and C2H2 respectively to discriminate between O depletion and C enhancement. We find that a disk structure characterised by the presence of a gap can best explain the observations. The inner disk is strongly depleted in dust, especially small grains ($<5\,\mu$m), and ..

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arXiv2025

MINDS. Cha H{\alpha} 1, a brown dwarf with a hydrocarbon-rich disk

Context. Recent JWST observations have shown that brown dwarfs (BD) are chemically rich, offering valuable insights into giant planet formation. Aims. As part of the MIRI mid-INfrared Disk Survey (MINDS) JWST guaranteed time program, we aim to characterize the gas and dust composition of the disk around the brown dwarf [NC98] Cha HA 1, hereafter Cha H$\alpha$ 1, in the mid-infrared. Methods. We obtain data from the MIRI Medium Resolution Spectrometer (MRS) from 4.9 to 28$\mu$m. We use the dust fitting tool DuCK to investigate the dust composition and grain sizes while we identify and fit molecular emission using slab models. Results. Compared with disks around very low mass stars, clear silicate emission features are seen in this BD disk. In addition, JWST reveals a plethora of hydrocarbons, including C$_2$H$_2$, $^{13}$CCH$_2$, CH$_3$, CH$_4$, C$_2$H$_4$, C$_4$H$_2$, C$_3$H$_4$, C$_2$H$_6$, and C$_6$H$_6$ which suggest a disk with a gas C/O > 1. Additionally, we detect CO$_2$, $^{13}$CO$_2$, HCN, H$_2$, and H$_2$O. CO and OH are absent from the spectrum. The dust is dominated by large $\sim$4 $\mu$m size amorphous silicates (MgSiO$_3$). We infer a small dust mass fraction ($>$10$\%$) of 5 $\mu$m size crystalline forsterite. We do not detect polycyclic aromatic hydrocarbons. Conclusions. Cha H$\alpha$ 1 shows the most diverse chemistry seen to date in a BD protoplanetary disk, consisting of a strong dust feature, 12 carbon-bearing molecules plus H$_2$, and water. The diverse molecular environment offers a unique opportunity to test our understanding of BD disks chemistry and how it affects the possible planets forming in them.

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arXiv2025

A transition from H$_2$O to C$_2$H$_2$ dominated spectra with decreasing stellar luminosity

The chemical composition of the inner regions of disks around young stars will determine the properties of planets forming there. Many disk physical processes drive the chemical evolution, some of which depend on/correlate with the stellar properties. We aim to explore the connection between stellar properties and inner disk chemistry, using mid-infrared spectroscopy. We use JWST-MIRI observations of a large, diverse sample of sources to explore trends between C$_2$H$_2$ and H$_2$O. Additionally, we calculate the average spectrum for the T Tauri ($M_{*}$$>$0.2 $M_{\odot}$) and very low-mass star (VLMS, $M_{*}$$\leq$0.2 $M_{\odot}$) samples and use slab models to determine the properties. We find a significant anti-correlation between the flux ratio of C$_2$H$_2$/H$_2$O and the stellar luminosity. Disks around VLMS have significantly higher $F_{\rm{C_2H_2}}$/$F_{\rm{H_2O}}$ flux ratios than their higher-mass counterparts. We also explore trends with the strength of the 10 $\mu$m silicate feature, stellar accretion rate, and disk dust mass, all of which show correlations with the flux ratio, which may be related to processes driving the carbon-enrichment in disks around VLMS, but also have degeneracies with system properties. Slab model fits to the average spectra show that the VLMS H$_2$O emission is quite similar in temperature and column density to a warm ($\sim$600 K) H$_2$O component in the T Tauri spectrum, indicating that the high C/O gas phase ratio in these disks is not due to oxygen depletion alone. Instead, the presence of many hydrocarbons, including some with high column densities, points to carbon enhancement in the disks around VLMS. The observed differences in the inner disk chemistry as a function of host properties are likely to be accounted for by differences in the disk temperatures, stellar radiation field, and the evolution of dust grains.

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arXiv2025

MINDS. Young binary systems with JWST/MIRI: Variable water-rich primaries and extended emission

As part of the JWST GTO program MINDS, we analyze the mid-infrared emission of three Class II binary systems: VW Cha, WX Cha, and RW Aur, to investigate the impact of stellar multiplicity on the chemistry and physics of their inner disk. We analyze the 1D spectrum from JWST/MIRI-MRS for primary and secondary disks separately, extracted by combining forward modeling with a theoretical PSF and aperture photometry. We modeled the molecular lines with 0D slab models. We interpret the results by comparing our JWST spectra to VLT/CRIRES+, Spitzer/IRS, and ALMA. Primary and secondary disks are dramatically different in their mid-infrared emission, with primary disks showing H2O-rich spectra, and secondary disks being mostly line poor to the sensitivity of our spectra. When comparing MIRI-MRS to Spitzer/IRS, we observe large variability in the line emission of VW Cha A, as well as in the continuum of RW Aur A. The disks around VW Cha BC and RW Aur B show evidence of ionizing radiation, and a further comparison with ALMA at high angular resolution dust continuum suggest that the spectrum of RW Aur B is well explained by its ~4 au cavity. All the systems show [Ne II] jet emission, and three of them also show spatially resolved emission structures in H2, likely originated by outflows and dynamical interactions. Many of the observed features in the primary disks, such as enhanced water emission, could be linked to the increased accretion and radial drift produced by dynamical disk truncation. However, additional mechanisms are needed to explain the large differences between primary and secondary disks, potentially inner disk substructures. This work is an example of the need for combining multiple facilities to fully understand the observations from JWST.

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arXiv2025

MINDS. Water reservoirs of compact planet-forming dust disk: A diversity of H$_2$O distributions

Millimetre-compact dust disks are thought to have efficient radial drift of icy dust pebbles, which has been hypothesised to produce an enhanced cold ($T<$400 K) H$_2$O reservoir in their inner disks. Mid-infrared spectral surveys, now with the James Webb Space Telescope (JWST), pave the way to explore this hypothesis. In this work, we test this theory for 8 compact disks ($R_\mathrm{dust}<$60 au) with JWST-MIRI/MRS observations. We analyse the different reservoirs that can be probed with the pure rotational lines ($>$10 $\mathrm{\mu}$m) through parametric column density profiles, multiple component slab models, and line flux ratios. We find that not all compact disks show strong enhancements of the cold H$_2$O reservoir, instead we propose three different classes of inner disk H$_2$O distributions. Four of our disks appear to have similar H$_2$O distributions as many of the large and structured disks (Type N or ``Normal'' disks), as is indicated by the slab model fitting and the line flux ratios. These disks have a small cold reservoir, suggesting the inward drift of dust, but it is not as efficient as hypothesised before. Only two disks do show a strong enhancement of the cold H$_2$O emission (Type E or cold H$_2$O enhanced disks), agreeing with the original hypothesis. The two remaining disks are found to be very H$_2$O-poor (Type P or H$_2$O-poor disks), yet show emission from either the hot or immediate reservoirs (depending on the fit) in addition to emission from the cold one. We find that different parametrisations are able to provide a good description of the observed H$_2$O spectra, with the multiple component analysis yielding similar results. Finally, we also report the detection of other molecules in these disks, including a tentative detection of CH$_4$ in CY Tau.

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arXiv2025

Can thermodynamic equilibrium be established in planet-forming disks?

The inner regions of planet-forming disks are warm and dense. The chemical networks used for disk modelling so far were developed for a cold and dilute medium and do not include a complete set of pressure-dependent reactions. The chemical networks developed for planetary atmospheres include such reactions along with the inverse reactions related to the Gibb's free energies of the molecules. The chemical networks used for disk modelling are thus incomplete in this respect. We want to study whether thermodynamic equilibrium can be established in a planet-forming disk. We identify the regions in the disk most likely to reach thermodynamic equilibrium and determine the timescale over which this occurs. We employ the theoretical concepts used in exoplanet atmosphere chemistry for the disk modelling with PROtoplanetary DIsk MOdel ({\sc ProDiMo}). We develop a chemical network called CHemistry Assembled from exoplanets and dIsks for Thermodynamic EquilibriA ({\sc ChaiTea}) that is based on the UMIST 2022, STAND, and large DIscANAlysis (DIANA) chemical networks. It consists of 239 species. From the STAND network, we adopt the concept of reversing all gas-phase reactions based on thermodynamic data. We use single-point models for a range of gas densities and gas temperatures to verify that the implemented concepts work and thermodynamic equilibrium is achieved in the absence of cosmic rays and photoreactions including radiative associations and direct recombinations. We then study the impact of photoreactions and cosmic rays that lead to deviations from thermodynamic equilibrium. We explore the chemical relaxation timescales towards thermodynamic equilibrium. Lastly, we study the predicted 2D chemical structure of a typical T\,Tauri disk when using the new {\sc ChaiTea} network instead of the large DIANA standard network, including photorates, cosmic rays, X-rays, and ice....

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arXiv2025

The effects of transport processes on the bulk composition of the first generation of planetesimals interior to the water iceline

The CHNOS elemental budgets of rocky planets are crucial for their structure, evolution and potential chemical habitability. It is unclear how the nonlocal disk processes affecting dust in planet-forming disks affect the CHNOS elemental budgets of nascent planets both inside and outside the Solar System. We aim to quantify the coupled effect of dynamical and collisional processes on the initial refractory CHNOS budgets of planetesimals, forming interior to the water ice line for a Solar and non-Solar composition consistent with the star HIP 43393. Methods. We utilize the SHAMPOO code to track the effects of dynamical and collisional processes on 16000 individual dust monomers. Each monomer is here assigned a refractory chemical composition and mineralogy informed by the equilibrium condensation code GGCHEM given the P-T conditions at the initial position of the monomer. Monomers travel embedded in aggregates through a young class I disk, whose structure is calculated with the ProDiMo code. Furthermore, monomers are allowed to undergo dehydration and desulfurization. We find that solid material becomes well-mixed both radially and vertically. For both the Solar and HIP43393 compositions, the solid phase in the disk midplane regions interior to r~0.7AU can become enriched in hydrogen and sulfur by up to 10at% relative to predictions from purely local calculations. This originates from the inward radial transport of hydrated and sulfur-bearing minerals such as lizardite and iron sulfide. Nonlocal disk processing in a young turbulent, massive disk can lead to significant compositional homogenization of the midplane dust and by extension of the initial composition of planetesimals. Planetesimals forming at r<0.7AU may become enriched in hydrated minerals and sulfur, which could result in more widespread aqueous alteration interior to the water iceline compared to planetesimals that emerge...

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