We present a homogeneous VLT/X-Shooter study of accretion in young stellar objects spanning the entire Orion A complex. Our sample includes 91 pre-main-sequence stars hosting a protoplanetary disk according to Spitzer photometry, of which 34 have complementary ALMA dust mass measurements. We derived stellar and accretion properties using a self-consistent multi-component fitting procedure. Our sample encompasses spectral types from K3 down to M5, corresponding to stellar masses within ∼0.8-0.1 M_⊙. The accretion-stellar luminosity (L_acc-L_⋆) and the mass accretion rate-stellar mass (Ṁ_acc-M_⋆) scaling relations in Orion A are consistent with those of other star-forming regions (SFRs) that span a range of stellar densities, far-ultraviolet (FUV) irradiation fields, and ages, with all regions occupying the same locus in parameter space. For the 34 sources with complementary dust mass measurements, we present the first investigation of the Ṁ_acc and disk mass (M_disk) correlation in Orion A, recovering a spread consistent with that reported for other regions. Despite our sample spanning nearly five orders of magnitude in local FUV field strength, we find no statistically significant correlation between Ṁ_acc and FUV irradiation. However, by combining our sample with literature measurements in Lupus, the Orion Nebula Cluster, and σ Orionis, we find a tentative population-level decrease of the inferred disk lifetime t_ disk =M_disk/Ṁ_acc toward stronger FUV environments, though large intrinsic scatter and limited sample sizes at intermediate and high FUV fields prevent firm conclusions. The homogeneous Ṁ_acc measurements reported here provide a solid foundation for future studies of accretion and disk evolution across the diverse environments of Orion A and other SFRs.

We investigate whether photoevaporation alone can open and sustain gaps in protoplanetary discs by coupling the evolving disc structure with the photoevaporative flow in two dimensional radiation hydrodynamical simulations. Our results show that once a density depression forms, the local mass-loss rate decreases sharply, suppressing further gap deepening. Viscous inflow and radial mass transport along the disc surface act to partially refill the depleted region, preventing complete clearing. The resulting configuration is a persistent, partially depleted zone whose evolution is largely insensitive to the initial disc morphology. This behaviour challenges the standard paradigm that photoevaporation efficiently carves clean inner cavities and directly produces transition discs. However, the pressure maximum at the outer edge of the depression may still trap dust grains, giving rise to transition disc like observational signatures. We also present a first-order prescription to approximate this behaviour in one dimensional disc evolution models, suitable for use in planet formation and population synthesis studies. Although the prescription improves upon static mass-loss treatments, it remains approximate, underscoring the need for further multidimensional simulations and parameter-space exploration to derive robust recipes for global disc and planet population models.

Context. The radio emission mechanisms from accreting protoplanets and their variability link observations and physical properties. Aims. We revisit the variability of the ∼343 GHz (ALMA Band 7) flux density from PDS 70c (FB7). Methods. The subtraction of the extended time-averaged signal may enable the measurement of the flux density from variable and embedded point sources. Visibility alignment and self-calibration yield close to thermal residuals in each execution block (EB) of ALMA observations, thus allowing the time-differential photometry of point-sources in the visibility domain. The variability of PDS 70c was checked against synthetic control point sources. Results. In images of the 2017 ALMA dataset, with three ∼1 h EBs, PDS 70c was detected only on 6 December 2017, where FB7 rose by 228%±69% (3.3σ). Time-differential photometry confirms a rise by 170%±46% (3.7σ). An application to ∼2 h EBs from the 2023 dataset resulted in constant flux densities, within a scatter of ∼15%. However, FB7(t) shows some scatter when splitting the deep 2023 EBs into 20 min intervals, with a χ2 test significant at 2.6σ, and an intrinsic dispersion of 49%±21%. Conclusions. The radio variability of PDS 70c, observed over hours but averaged out on longer timescales, is indeed expected if the signal is due to H I free-free from an accretion shock on a circumplanetary disk surface. A planet-to-environment mass ratio < 10−4 is required to avoid smoothing by radiative diffusion if the signal is due to thermal emission from the environment.

Hydrogen-isotopologues are commonly used to trace the chemical processing and origin of hydrogen-bearing species throughout the Universe, however, their abundance remains unconstrained for extrasolar planets. Here, we report atmospheric retrieval evidence for the deuterated water molecule HDO in an exoplanet atmosphere, retrieved from James Webb Space Telescope transmission spectra of the hot Jupiter WASP-39 b, resulting in a deuterium-to-hydrogen ratio in water of 4.0^+1.3_-1.1× 10^-3. The inferred value is substantially higher than those measured for the Solar System gas giants and overlaps numerically with values reported for some protostellar and inner Solar System environments. This enrichment may reflect either inherited water-rich material accreted beyond the snow line or isotopic processing in the observable atmosphere through transport, photochemistry, and subsequent escape.

Compact protoplanetary discs are becoming increasingly prominent in observations. Their dispersal pathways may differ substantially from those of extended discs. We aim to quantify the role of the disc outer radius in internal photoevaporation, provide a simple scaling relation for compact discs, and test whether the resulting evolutionary tracks reproduce the observed inside-out clearing of young stellar populations. We performed radiation-hydrodynamic simulations of X-ray-driven photoevaporation for discs with different outer radii, and derived the dependence of the total mass-loss rate on the cut-off radius. We find that the surface mass-loss profiles are nearly independent of disc size, but their integrated wind rates are reduced according to the cumulative mass-loss rate distribution. We incorporated this scaling into disc population synthesis models. When the internal photoevaporation is applied only up to the cut-off radius compact discs evolve via inside-out clearing consistent with observational diagnostics, while when the cut-off radius is not considered, the disc spreading is hindered and the disc dispersal proceeds from the outside-in. The introduction of mild external photoevaporation present in nearby star forming regions cannot prevent the disc spreading when the cut-off radius prescription is included, but it can much better explain the evolution of disc radii as a function of time. Disc dispersal prescriptions must include the dependence on disc cut-off radius to capture the evolution of compact discs. The proposed scaling provides a simple, physically motivated correction that better predicts the growing observational evidence for compact discs and inside-out dispersal.

Protoplanetary disks represent a crucial stage in the evolution of Young Stellar Objects towards the formation of fully formed planetary systems. While substantial progress has been made in the last decades in the characterization of the dust and molecular gas in these systems, the ionized component remains poorly understood. Ionized gas traces important processes such as photoevaporation, accretion, disk winds, and jets, and therefore is key to studying disk dynamics, evolution, and ultimately planet formation. In this paper, we investigate the capabilities of the forthcoming SKA telescope to probe this component in protoplanetary disks within nearby star forming regions. We present state-of-the-art simulations of photoevaporative, magneto-thermal, and magnetohydrodynamic winds, and generate theoretical predictions and synthetic SKAO observations to assess its potential in detecting and characterizing free-free emission and Hydrogen recombination lines. Finally, we discuss synergies with complementary facilities and how they will provide a comprehensive, multi-scale view of disk winds and offer critical insights on the mechanisms driving disk evolution and the onset of planet formation.

Exomoons around free-floating planets (FFPs) can survive their host planet's ejection. Such ejections can increase their orbital eccentricity, providing significant tidal heating in the absence of any stellar energy source. Previous studies suggested that liquid water could exist on such moons under thick CO_2-dominated atmospheres, but these models faced challenges with CO_2 condensation and atmospheric collapse, particularly in the high-pressure regimes that favoured long-term habitability. To address this, we employ a self-consistent model, including radiative transfer and equilibrium chemistry with condensation, to simulate a more stable hydrogen-dominated atmosphere for a range of initial chemical compositions, including C, O, and N. We find that such atmospheres can effectively trap heat via collision-induced absorption of H_2, maintaining surface temperatures suitable for liquid water for time-scales of up to 4.3 Gyr, depending on the surface pressure, while not prone to condensation-induced collapse. Wet-dry cycling caused by the strong tides together with the alkalinity of dissolved NH_3 could create favourable conditions for RNA polymerisation and thus support the emergence of life.

PDS 70c is a source of Ha emission and variable sub-mm signal. Understanding its emission mechanisms may enable observations of accretion rates and physical conditions in the circum-planetary environment. We report ALMA observations of PDS 70 at 145 GHz (Band 4), 343.5 GHz (Band 7) and 671 GHz (Band 9) and compare with data at 97.5 GHz (Band 3), taken within two months. The radio spectrum (SED) is analyzed with an analytical circumplanetary disk (CPD) model. In a novel approach including the free-free continuum from H I, metals (e.g. K I) and H-. New detections in Bands 3 (tentative at 2.6sigma), 4 (5sigma), and 7 (re-detected at 9sigma) are consistent with optically thick thermal emission from PDS 70c (spectral index 2+-0.2). However, a Band 9 non-detection lies 2.6sigma below an optically thick extrapolation. A viscous dusty disk is inconsistent with the data, even with the inclusion of ionised jets. Interestingly, the central temperatures in such CPD models are high enough to ionise H I, with huge emission measures and an optically thick spectrum that marginally accounts for the SED (within 3sigma of Band 9). By contrast, uniform-slab models suggest much lower emission measures to account for the Band 9 drop, with ionisation fractions 1e-7, and an outer radius 0.1 au. Such conditions are recovered if the CPD interacts with a planetary magnetic field, leading to a radially variable viscosity alpha(R)< 1 and midplane temperatures 1e3 K that regulate metal ionisation. However, the H- opacity still results in an optically thick SED, overshooting Band 9. We find that the optically thin turnover at 600 GHz is only recovered if a thin shocked layer is present at the CPD surface, as suggested by simulations. A photospheric shock or accretion funnels are ruled out as radio emission sources because their small solid angles would require T 1e6 K, which is unrealistic for planetary accretion.

AI is set to play a crucial role in the future of space missions, enabling autonomous rover navigation, landing procedures, and terrain analysis. For these systems to perform reliably, they must be trained on large volumes of high-quality, task-specific data. However, in space science, data is often limited due to the high costs and power demands of transmission, and more critically it is not fully controllable. Synthetic data offers a promising solution by being both controllable and significantly more cost- and time-efficient. Yet, for synthetic data to genuinely enhance model performance, its quality must be rigorously evaluated. This work addresses that challenge by assessing the quality of synthetic data generated with StyleGAN2-ADA, trained on HiRISE imagery. An evaluation pipeline was developed to analyze the data using a range of established metrics. At the same time, it examines the reliability and relevance of these metrics themselves. The findings reveal a perceptual mismatch between model-based feature extractors and human judgment, raising concerns about the trustworthiness of current evaluation practices.

Context. Transition disks (TDs) are a type of protoplanetary disk characterized by a central dust and gas cavity. The processes behind how these cavities are formed and maintained, along with their observed high accretion rates of 10-8-10-7 M circle dot yr-1, continue to be subjects of active research.Aims. This work aims to investigate how the inclusion of the Hall effect (HE) alongside Ohmic resistivity (OR) and ambipolar diffusion (AD) affects the structure of the TD. Of key interest is the dynamical evolution of the cavity and whether it can indeed produce transonic accretion, as predicted by theoretical models in order to account for the observed high accretion rates despite the inner disk's low density.Methods. We present our results of 2D axisymmetric global radiation magnetohydrodynamic (MHD) simulations of TDs for which all three non ideal MHD effects are accounted. We used the NIRVANA-III fluid code and initialized our model with a disk cavity reaching up to R = 8 au with a density contrast of 105 . We performed three runs, one with only OR and AD, and one for each of the two configurations that arise when additionally including the HE, that is, with the field aligned (anti-aligned) with respect to the rotation axis.Results. For all three runs, our models maintain an intact inner cavity and an outer standard disk. MHD winds are launched both from the cavity and from the disk. Notably, when the HE is included, ring-like structures develop within the cavity. We moreover obtain accretion rates of 3-8 x 10-8 M circle dot yr-1, comparable to typical values seen in full disks. Importantly, we clearly observe (tran)sonic accretion (vacc greater than or similar to cs) in the cavity. Additionally, outward magnetic flux transport occurs in all three runs.

Context. Dust dynamics plays a critical role in astrophysical processes and has been modeled in hydrodynamical simulations using various approaches. Among particle-based methods like Smoothed Particle Hydrodynamics (SPH), the One-Fluid model has proven to be highly effective for simulating gas-dust mixtures. Aims. This study presents the implementation of the One-Fluid model in OpenGadget3, introducing improvements to the original formulation. These enhancements include time-dependent artificial viscosity and conductivity, as well as a novel treatment of dust diffusion using a pressure-like term. Methods. The improved model is tested using a suite of dust dynamics benchmark problems: DUSTYBOX, DUSTYWAVE, and DUSTYSHOCK, with the latter extended to multidimensional scenarios, as well as a dusty Sedov-Taylor blast wave. Additional tests include simulations of Cold Keplerian Disks, dusty protoplanetary disks, and Kelvin-Helmholtz instabilities to evaluate the model's robustness in more complex flows. Results. The implementation successfully passes all standard benchmark tests. It demonstrates stability and accuracy in both simple and complex simulations. The new diffusion term improves the handling of flows with large dust-to-gas ratios and low drag coefficients, although limitations of the One-Fluid model in these regimes remain. Conclusions. The enhanced One-Fluid model is a reliable and robust tool for simulating dust dynamics in OpenGadget3. While it retains some limitations inherent to the original formulation, the introduced improvements expand its applicability and address some challenges in gas-dust dynamics.

Polycyclic aromatic hydrocarbons (PAHs) are prevalent in the Universe and interstellar medium but are primarily attributed to anthropogenic sources on Earth, such as fossil fuel combustion and firewood burning. Drawing upon the idea of PAHs being suitable candidates for technosignatures, we investigate the detectability of those PAHs that have available absorption cross sections in the atmospheres of Earth-like exoplanets (orbiting G-type stars at a distance of 10 pc) with an 8 m mirror of the Habitable Worlds Observatory (HWO). Specifically, we focus on Naphthalene, Anthracene, Phenanthrene, and Pyrene. Our simulations indicate that under current-Earth-like conditions, detecting PAH signatures between 0.2 and 0.515 μ m is infeasible. To account for the historical decline in PAH production post the industrial revolution, we explore varying PAH concentrations to assess instrumental capabilities of detecting civilizations resembling modern Earth. We also evaluate telescope architectures (6 m, 8 m, and 10 m mirror diameters) to put our results into the context of the future HWO mission. With these four molecules, PAH detection remains infeasible, even at concentrations 10 times higher than current levels. While larger mirrors provide some advantages, they fail to resolve the spectral signatures of these molecules with significant signal-to-noise ratios. The UV absorption features of PAHs—caused by π -orbital → π *-orbital electronic transitions—serve as valuable markers, due to their distinct and detectable nature, preserved by the aromatic stability of PAHs. Additional lab measurements are necessary to gather absorption cross-sectional data beyond UV for more abundant PAHs. This may help further in improving the detectability of these molecules.

Context . Disc winds driven by thermal and magnetic processes are thought to play a critical role in protoplanetary disc evolution. However, the relative contribution of each mechanism remains uncertain, particularly in light of their observational signatures. Aims . We investigate whether spatially resolved emission and synthetic spectral line profiles can be used to distinguish between thermally and magnetically driven winds in protoplanetary discs. Methods . We modelled three disc wind scenarios with different levels of magnetisation: a relatively strongly magnetised wind ( β 4), a rather weakly magnetised wind ( β 6), and a purely photoevaporative wind ( PE ). Using radiative transfer post-processing, we generated synthetic emission maps and line profiles for [OI] 6300 Å, [NeII] 12.81 μm, and o-H 2 2.12 μm, and compared them with observational trends in the literature. Results . We find that the β 4 model generally produces broader and more blueshifted low-velocity components across all tracers, consistent with compact emission regions and steep velocity gradients. The β 6 and PE models yield narrower profiles with smaller blueshifts, in better agreement with most observed narrow low-velocity components (NLVCs). We also find that some line profile diagnostics, such as the inclination at maximum centroid velocity, are not robust discriminants. However, the overall blueshift and full width at half maximum of the low-velocity components provide reliable constraints. The β 4 model reproduces the most extreme blueshifted NLVCs in observations, while most observed winds are more consistent with the β 6 and PE models. Conclusions . Our findings reinforce previous conclusions that most observed NLVCs are compatible with weakly magnetised or purely photo-evaporative flows. The combination of line kinematics and emission morphology offers meaningful constraints on wind-driving physics, and synthetic line modelling remains a powerful tool for probing disc wind mechanisms.

The integration of aerodynamic drag is a fundamental step in simulating dust dynamics in hydrodynamical simulations. We propose a novel integration scheme, designed to be compatible with Strang splitting techniques, which allows for the straightforward integration of external forces and hydrodynamic fluxes in general-purpose hydrodynamic simulation codes. Moreover, this solver leverages an analytical solution to the problem of drag acceleration, ensuring linear complexity even in cases with multiple dust grain sizes, as opposed to the cubic scaling of methods that require a matrix inversion step. This new general implicit Runge–Kutta (GIRK) integrator is evaluated using standard benchmarks for dust dynamics such as DUSTYBOX, DUSTYWAVE, and DUSTYSHOCK. The results demonstrate not only the accuracy of the method but also the expected scalings in terms of accuracy, convergence to equilibrium, and execution time. GIRK can be easily implemented in hydrodynamical simulations alongside hydrodynamical steps and external forces and is especially useful in simulations with a large number of dust grain sizes.

Aims. PDS 70c is a source of H alpha emission and variable sub-millimetre signal. Knowledge of the emission mechanisms may enable observations of accretion rates and physical conditions in the circumplanetary environment. Methods. We report ALMA observations of PDS 70 at 145 GHz (Band 4), 343.5 GHz (Band 7), and 671 GHz (Band 9) and compare them with archival data at 97.5 GHz (Band 3). The derived radio spectral energy distribution (SED) of PDS 70c is coeval within two months, and is interpreted in terms of analytic models of dusty and viscous discs (i.e. circumplanetary discs, CPDs). In a novel approach, we include the free-free continuum from H I, metals (e.g. K I) and H-. Results. New detections in Bands 3 (tentative at 2.6 sigma), 4 (5 sigma), and 7 (re-detected at 9 sigma) are consistent with optically thick thermal emission from PDS 70c (spectral index alpha = 2 +/- 0.2). However, a non-detection in Band 9 breaks this trend, with a flux density falling below an optically thick extrapolation at 2.6 sigma. A viscous dusty disc is inconsistent with the data, even with the inclusion of ionised jets. Interestingly, the central temperatures in such CPD models are high enough to ionise H I, with huge emission measures and an optically thick spectrum that marginally accounts for the radio SED (within 3 sigma of Band 9). Since there is no room for steeper components (with alpha > 2), the dust-to-gas ratio is lower than 10(-5). By contrast, uniform-slab models suggest much lower emission measures to account for the Band 9 drop, with ionisation fractions of similar to 10(-7) and an outer radius of similar to 0.1 au. Such conditions are recovered if the CPD interacts with a planetary magnetic field, leading to a radially variable viscosity, alpha(R) less than or similar to 1, and central temperatures of similar to 10(3) K that regulate metal ionisation. However, the H- opacity still results in an optically thick SED, overshooting Band 9. We find that the optically thin turnover at greater than or similar to 600 GHz is only recovered if a thin shocked layer is present at the CPD surface, as is suggested by simulations. A photospheric shock or accretion funnels are ruled out as radio emission sources because their small solid angles require T similar to 10(6) K, which are unrealistic temperatures in planetary shock accretion. Conclusions. The SED of PDS 70c collected here is optically thick up to Band 7 but probably (2.6 sigma) turns over towards Band 9. An optically thick spectrum can be explained by atomic plasma radiation from a magnetised disc, where the radio opacity stems from metal and H- free-free. If so, PDS 70c is depleted of sub-millimetre-emitting dust by a factor of at least 1000. However, the turnover can only be accounted for by H I free-free from an accretion shock at the surface of a CPD.

When observing transmission spectra produced by the atmospheres of ultra-hot Jupiters (UHJs), large telescopes are typically the instrument of choice given the very weak signal of the planet's atmopshere. The aim of the present study is to demonstrate that, for favourable targets, smaller telescopes are fully capable of conducting high-resolution cross-correlation spectroscopy. We apply the cross-correlation technique to data from the 2.1 m telescope at the Wendelstein Observatory, using its high-resolution spectrograph FOCES, in order to demonstrate its efficacy in resolving the atmosphere of the UHJ KELT-9 b. Using three nights of observations with the FOCES spectrograph and one with the HARPS-N spectrograph, we conduct a performance comparison between FOCES and HARPS-N. This comparison considers both single-transit and combined observations over the three nights. We then consider the potential of 2 m class telescopes by generalising our results to create a transit emulator capable of evaluating the potential of telescopes of this size. With FOCES, we detected seven species in the atmosphere of KELT-9b: Ti II, Fe I, Fe II, Na I, Mg I, Na II, Cr II, and Sc II. Although HARPS-N surpasses FOCES in performance thanks to the mirror of the TNG, our results reveal that smaller telescope classes are capable of resolving the atmospheres of UHJs given sufficient observing time. This broadens the potential scope of such studies, demonstrating that smaller telescopes can be used to investigate phenomena such as temporal variations in atmospheric signals and the atmospheric loss characteristics of these close-in planets.

Context. Disc winds and planet–disc interactions are two crucial mechanisms that define the structure, evolution, and dispersal of protoplanetary discs. While winds are capable of removing material from discs, eventually leading to their dispersal, massive planets can shape their disc by creating sub-structures such as gaps and spiral arms. Aims. We studied the interplay between an X-ray photoevaporative disc wind and the sub-structures generated due to planet–disc interactions to determine how their mutual interactions affect the disc’s and the planet’s evolution. Methods. We performed 3D hydrodynamic simulations of viscous discs (α = 6.9 × 10−4) that host a Jupiter-like planet and undergo X-ray photoevaporation. We traced the gas flows within the disc and wind and measured the rate of accretion onto the planet, as well as the gravitational torque that is acting on it. Results. Our results show that the planetary gap removes the wind’s pressure support, allowing wind material to fall back into the gap. This opens new pathways for material from the inner disc (and part of the outer disc) to be redistributed through the wind towards the gap. Consequently, the gap becomes shallower and the flow of mass across the gap in both directions is significantly increased, as is the planet’s mass-accretion rate (by factors of ≈5 and ≈2, respectively). Moreover, the wind-driven redistribution results in a denser inner disc and a less dense outer disc, which, combined with the recycling of a significant portion of the inner wind, leads to longer lifetimes for the inner disc, contrary to the expectation in a planet-induced photoevaporation scenario that has been proposed in the past.

Understanding the complex evolution of protoplanetary disks (PPDs) and their dispersal via energetic stellar radiation are prominent challenges in astrophysics. It has recently been established that specifically the X-ray luminosity from the central protostar can significantly heat the surface of the disk, causing powerful photoevaporative winds that eject a considerable fraction of the disc's mass. Recent work in the field has moreover shown the importance of global PPD simulations that simultaneously take into account non-ideal magnetohydrodynamic (MHD) effects and detailed thermochemistry. Our motivation with the current paper lies in combining these two aspects and figure out how they interact. Focus is put on the Hall Effect (HE) and the impact it has on the overall field topology and mass loss/accretion rates. Utilizing a novel X-ray temperature parametrisation, we perform 2D-axisymmetric MHD simulations with the NIRVANA fluid code, covering all non-ideal effects. We find that, in the aligned orientation, the HE causes prominent inward displacement of the poloidal field lines that can increase the accretion rate through a laminar Maxwell stress. We find that outflows are mainly driven by photoevaporation -- unless the magnetic field strength is considerable (i.e., $\beta_p\leq 10^{3}$) or the X-ray luminosity low enough (i.e., $\log{L_X}\leq 29.3$). Inferred mass loss rate are in the range of the expected values $10^{-8}$ to $10^{-7}M_{\odot}yr^{-1}$. For comparison, we have also performed pure hydrodynamic (HD) runs and compared them with the equivalent MHD runs. Here we have found that the magnetic field does indeed contribute to the mass loss rate, albeit only discernibly so for low enough $L_X$ (i.e., $\log{L_X}\leq 30.8$). For values higher than that, the wind mass loss predicted from the MHD set converges to the ones predicted from pure HD.

Polycyclic Aromatic Hydrocarbons (PAHs) have been detected throughout the universe where they play essential roles in the evolution of their environments. For example, they are believed to affect atmospheric loss rates of close-in planets and might contribute to the pre-biotic chemistry and emergence of life. Despite their importance, the study of PAHs in exoplanet atmospheres has been limited. We aim to evaluate the possibility of detecting PAHs on exoplanets considering future observations using JWST's NIRSpec PRISM mode. The hot Saturn WASP-6 b shows properties that are consistent with a potential PAH presence and is thus used as a case study for this work. Here, we compare the likelihoods of various synthetic haze species and their combinations with the influence of PAHs on the transmission spectrum of WASP-6 b. This is possible by applying the atmospheric retrieval code petitRADTRANS to a collection of data from previous observations. Subsequently, by exploring synthetic, single transit JWST spectra of this planet that include PAHs, we assess if these molecules can be detected in the near future. Previous observations support the presence of cloud/haze species in the spectrum of WASP-6 b. While this may include PAHs, the current data do not confirm their existence unambiguously. Our research suggests that utilizing the JWST for future observations could lead to a notable advancement in the study of PAHs. Employing this telescope, we find that a PAH abundance of approximately 0.1 per cent of the ISM value could be robustly detectable.

Context: Photoevaporation is an important process for protoplanetary disc dispersal but there has so far been a lack of consensus from simulations over the mass-loss rates and the most important part of the high-energy spectrum for driving the wind. Aims: We aim to isolate the origins of these discrepancies through carefully-benchmarked hydrodynamic simulations of X-ray photoevaporation with time-dependent thermochemistry calculated on the fly. Methods: We conduct hydrodynamic simulations with pluto where the thermochemistry is calculated using prizmo. We explore the contribution of certain key microphysical processes and the impact of using different spectra used previously in literature studies. Results: We find that additional cooling results from the excitation of O by neutral H, which leads to dramatically reduced mass-loss across the disc compared to previous X-ray photoevaporation models, with an integrated rate of 10^-9 Msun/yr. Such rates would allow for longer-lived discs than previously expected from population synthesis. An alternative spectrum with less soft X-ray produces mass-loss rates around a factor of 2-3 times lower. The chemistry is significantly out of equilibrium, with the survival of H2 into the wind aided by advection. This leads to its role as the dominant coolant at 10s au - thus stabilising a larger radial temperature gradient across the wind - as well as providing a possible wind tracer.