Icy grain mantles play a crucial role in the chemistry of star-forming regions, allowing reactions that contribute to the formation of astrophysically complex organic molecules (COMs), including acetaldehyde (CH3CHO) and formamide (NH2CHO). Both compounds are also revealed in cometary comae. Laboratory experiments allowed us to reveal the formation of acetaldehyde and formamide in ices exposed to energetic sources, suggesting that the exposure of icy mantles and surfaces to Galactic cosmic rays (GCR) and solar charged particles triggers the formation of COMs. In this article, we provide data on the relevance of the initial ice composition on the formation and abundance of acetaldehyde and formamide. Furthermore, we aim to understand the time scales required in young star-forming regions to form both compounds through the ion-bombardment of icy grain mantles. We simulated the exposure of icy grain mantles to energetic charged particles in the laboratory. We produced a large set of icy mixtures comprising various molecules detected toward the solid phase of star-forming regions, including H2O, CO, CH3OH, CH4, NH3, and N2, and we exposed them to 200 keV H+ at 17 K simulating low-energy GCR. We followed the chemical evolution of ices by means of infrared spectroscopy. In the spectra, we looked for absorption features attributed to acetaldehyde (7.40 mu m) and formamide (7.20 mu m). We also provide estimations of their abundance as a function of the dose in the various investigated mixtures. The analysis revealed that the ice composition plays a primary role in both the destruction of the deposited species and the formation of new compounds. Water-methanol-ammonia mixtures are the most efficient in the formation of both COMs. The time scales required for their formation fall in the typical lifetimes of pre- and protostellar phases and strongly depend on the cosmic-ray ionization rate taken into account. We show that ices exposed to energetic ions can form both acetaldehyde and formamide. Abundances are found to be strongly related to the initial ice composition. We thus suggest that the bombardment of icy grain mantles by GCR is a relevant player in the formation of both compounds in the lifetime of pre- and protostellar objects.

Deuterium fractionation is highly efficient during the early stages of star formation, particularly in starless and prestellar cores where temperatures are low (<10 K) and molecular freeze-out onto dust grains is significant. Methanol forms early in these environments following CO freeze-out via successive hydrogenation reactions on grain surfaces, while the production of deuterated methanol requires elevated gas-phase D/H ratios generated through dissociative recombination of deuterated H-3(+). Consequently, large abundances of deuterated methanol are observed towards young stellar objects where prestellar ices have recently sublimated. Here, we present laboratory broadband infrared spectra of methanol and its isotopologues in astrophysical ice analogues, complemented by anharmonic vibrational calculations used to guide band assignments. Experiments were performed at the CASICE laboratory using a Bruker Vertex 70v spectrometer coupled to a closed-cycle helium cryostat, with isotopologue ices deposited at 10 K under high-vacuum conditions. Infrared transmission spectra were recorded over 6000 to 30 cm(-1) (1.67 to 333 & micro;m) and compared with spectra of pure isotopologue ices. Distinctive mid-infrared band patterns are identified for each deuterated species. In particular, CH2DOH exhibits a characteristic doublet at 1293 cm(-1) and 1326 cm(-1) (7.73 & micro;m and 7.54 & micro;m), while CHD2OH shows a similar doublet at 1301 cm(-1) and 1329 cm(-1) (7.69 & micro;m and 7.52 & micro;m), both remaining largely invariant across all studied ice mixtures. These robust spectral signatures provide reliable tracers for identifying deuterated methanol in JWST observations and for constraining astrochemical gas-grain models of deuterium enrichment prior to star and planet formation.

About 350 molecules have been identified in the interstellar medium (ISM), including complex molecules relevant to prebiotic chemistry. A remarkable level of molecular diversity has been observed from the earliest stages of star formation, providing the initial chemical inventory inherited by planetary systems. Radio observations have played a pivotal role in these discoveries, starting with the identification of the first polyatomic molecule, NH_3 (Cheung et al. 1968). (Sub-)millimeter observations have revealed complex organic molecules of prebiotic relevance, including formamide (NH_2CHO), glycolaldehyde (CH_2OHCHO), and even urea ((NH_2)_2CO), and hydroxylamine (NH_2OH), which are possible precursors of RNA nucleotides (Ceccarelli et al. 2023; Jiménez-Serra et al. 2020). However, in dense protostellar regions, dust opacity hampers the detection of molecular emission. Additionally, large molecules and those containing heavy atoms, which have rotational transitions at lower frequencies, often remain inaccessible to current instruments. The Square Kilometre Array Observatory (SKAO) will provide an unprecedented combination of sensitivity and angular resolution at radio wavelengths. This will allow for the detection of prebiotic species and offer new insights into the chemical pathways that shape emerging planetary systems (Jiménez-Serra et al. 2022). This chapter details the scientific questions and advancements that the SKAO, and more specifically, SKA-Mid equipped with the Band 5 receivers, will pursue in the field of astrochemistry, focusing on the chemical complexity in both high-mass and solar-type star-forming regions.

The rapid expansion of human space exploration highlights the need for advanced materials capable of enduring the severe conditions of extraterrestrial environments. Polymeric materials, such as polyetherimide (PEI), are extensively used in aerospace applications due to their low density, mechanical versatility, and partial shielding capacity against radiation. Nevertheless, prolonged exposure to hostile factors such as galactic cosmic rays, solar energetic particles, solar wind ions, atomic oxygen, and electromagnetic radiation results in progressive structural degradation manifested as erosion, mass loss, and deterioration of mechanical, thermal, and optical properties. To mitigate these effects, inorganic protective layers, particularly metal oxides, have been investigated because of their high hardness, chemical stability, and erosion resistance. Despite these advantages, issues related to interfacial adhesion and long-term stability of such protective layers remain significant challenges.The present study reports a novel covalent silica-based passivation approach for PEI, achieved through a multi-step chemical functionalization of the polymer surface. The process involves: i) the partial hydrolysis of imidic ring on PEI film surface, forming polyamic acid (PAA) layer; ii) chemical reduction of the carboxylic acid of PAA to benzylic alcohol groups; iii) grafting tetraethyl orthosilicate to benzyl alcohol moieties. The procedures were monitored using ATR-FT-IR, DSR-UV-Vis, contact angle, and SEM-EDX analyses.To evaluate the shielding efficacy of the obtained system, both pristine PEI and silica-coated PEI samples were exposed to simulated fast solar ions flux.The experimental results confirm the increased resistance to erosion of the silica shielded material compared to that of untreated PEI. Finally, to assess the applicability of the material in real-scenarios, a computer simulation was performed to estimate the energy dose for the proposed material as a function of the radius for different space orbits.

The spectral analysis of CM meteorites can help to constrain the mineralogical composition of their parent body, the C-type asteroids. The CM2 NWA 12184 was spectrally examined employing seven complementary techniques at different spatial resolutions, including VIS-to-MIR reflectance and Raman spectroscopy. Furthermore, the effects of space weathering on asteroids can be investigated by performing laboratory simulations on meteorites samples; thus, the meteorite was processed with He+ ions at 200 keV (maximum fluence of 1.0 x 1017 ions cm-2) to simulate the solar wind irradiation on C-type asteroids. We discriminated the mineralogical composition of the NWA 12184 at the millimeter scale and at the micrometer scale, investigating both matrix and chondrules. The ion experiment produced spectral darkening, reddening, shifting of the hydration band, and weakening of the absorption band ascribed to olivine in the VIS-NIR range, as well as the reduction in the olivine's peak in MIR range, clue of the sample's amorphization. The study identified the native mineralogy of the meteorite, the products of terrestrial weathering, and the aqueous and thermal alteration experienced by the parent body of the sample.

Ozone (O3) is considered among the most promising biosignatures to look for inside and outside the solar system, i.e., in planetary atmospheres and surfaces as well as in the atmosphere of exoplanets. Recent studies show that the O3 detection in exoplanetary atmospheres is already achievable with the James Webb Space Telescope (JWST) and also the search for O3 ice on the surface of several icy worlds will be soon possible thanks to the JUpiter ICy moons Explorer (JUICE) and Europa Clipper space missions (in addition to JWST). In this context, we noticed that there is a lack of insight when considering the possible radiolytic production of O3 within ices of different oxygen-bearing species which may be found on icy extraterrestrial surfaces (and consequently also released to enrich their atmospheres). We report here a comparative laboratory study on the production of O3 from several ion irradiated ices and icy mixtures: CO, CO:N2, CO:SO2, CO2, H2O:CO2, N2O, NO2:N2O4, and pure O2. The samples were processed with 200 keV protons (unless otherwise specified) and analyzed by Fourier Transform Infrared (FTIR) spectroscopy at 16 K. Our aim is to contribute to the understanding of how much O3 could be produced by energetic charged particles irradiating different oxygen-bearing ice species and compare these results to the case of O2 ice. We believe that the results presented in the current study may have a great scientific impact, especially in view of the future exploration of the icy worlds of the solar system and the current and future exploration of exoplanets by the ongoing and the upcoming space missions.

Context. Protostars contain icy ingredients necessary for the formation of potential habitable worlds, therefore, it is crucial to understand their chemical and physical environments. This work is focused on the ice features towards the binary protostellar system Ced 110 IRS4A and IRS4B, separated by 250 au and observed with James Webb Space Telescope (JWST) as part of the Early Release Science (ERS) Ice Age collaboration. Aims. This study is aimed at exploring the JWST observations of the binary protostellar system Ced 110 IRS4A and IRS4B primarily to unveil and quantify the ice inventories towards these sources. Finally, we compare the ice abundances with those found for the same molecular cloud. Methods. We used data from multiple JWST instruments (NIRSpec, NIRCam, and MIRI) to identify and quantify ice species in the Ced 110 IRS4 system. The analysis was performed by fitting or comparing the laboratory infrared spectra of ices to the observations. Spectral fits are carried out with the ENIIGMA fitting tool that searches for the best fit out of a large number of solutions. The degeneracies of the fits are also addressed and the ice column densities are calculated. In cases where the full nature of the absorption features is not yet known, we explore different laboratory ice spectra to compare them with the observations. Results. We provide a list of securely and tentatively detected ice species towards the primary and the companion sources. For Ced 110 IRS4B, we detected the major ice species H2O, CO, CO2, and NH3. All species are found in a mixture except for CO and CO2, which have both mixed and pure ice components. In the case of Ced 110 IRS4A, we detected the same major species as in Ced 110 IRS4B, as well as the following minor species: CH4, SO2, CH3OH, OCN-, NH4+, and HCOOH. A tentative detection of N2O ice (7.75 mu m), forsterite dust (11.2 mu m), and CH3+ gas emission (7.18 mu m) in the primary source was also made. Compared with the two lines of sight towards background stars in the Chameleon I molecular cloud, the protostar exhibits similar ice abundances, except in the case of the ions that are higher in IRS4A. The most clear differences are the absence of the 7.2 and 7.4 mu m absorption features due to HCOO- and icy complex organic molecules in IRS4A. There is also evidence of thermal processing in both IRS4A and IRS4B, as probed by the CO2 ice features. Conclusions. We conclude that the binary protostellar system Ced 110 IRS4A and IRS4B has a large inventory of icy species. The similar ice abundances in comparison to the starless regions in the same molecular cloud suggests that the chemical conditions of the protostar were set at earlier stages in the molecular cloud. It is also possible that the source inclination and complex geometry cause a low column density along the line of sight, which hides the bands at 7.2 and 7.4 mu m. Finally, we highlight that a comprehensive analysis using radiative transfer modelling is needed to disentangle the spectral energy distributions of these sources.

Context.Mid-infrared emission features are important probes of the properties of ionized gas and hot or warm molecular gas, which are difficult to probe at other wavelengths. The Orion Bar photodissociation region (PDR) is a bright, nearby, and frequently studied target containing large amounts of gas under these conditions. Under the “PDRs4All” Early Release Science Program for JWST, a part of the Orion Bar was observed with MIRI integral field unit (IFU) spectroscopy, and these high-sensitivity IR spectroscopic images of very high angular resolution (0.2″) provide a rich observational inventory of the mid-infrared (MIR) emission lines, while resolving the HIIregion, the ionization front, and multiple dissociation fronts.Aims.We list, identify, and measure the most prominent gas emission lines in the Orion Bar using the new MIRI IFU data. An initial analysis summarizes the physical conditions of the gas and demonstrates the potential of these new data and future IFU observations with JWST.Methods.The MIRI IFU mosaic spatially resolves the substructure of the PDR, its footprint cutting perpendicularly across the ionization front and three dissociation fronts. We performed an up-to-date data reduction, and extracted five spectra that represent the ionized, atomic, and molecular gas layers. We identified the observed lines through a comparison with theoretical line lists derived from atomic data and simulated PDR models. The identified species and transitions are summarized in the main table of this work, with measurements of the line intensities and central wavelengths.Results.We identified around 100 lines and report an additional 18 lines that remain unidentified. The majority consists of HIrecombination lines arising from the ionized gas layer bordering the PDR. The HIline ratios are well matched by emissivity coefficients from H recombination theory, but deviate by up to 10% because of contamination by HeIlines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni. We show how the NeIII/NeII, SIV/SIII, and ArIII/ArIIratios trace the conditions in the ionized layer bordering the PDR, while FeIII/FeIIand NiIII/NiIIexhibit a different behavior, as there are significant contributions to FeIIand NiIIfrom the neutral PDR gas. We observe the pure-rotational H2lines in the vibrational ground state from 0–0S(1) to 0–0S(8), and in the first vibrationally excited state from 1–1S(5) to 1–1 S(9). We derive H2excitation diagrams, and for the three observed dissociation fronts, the rotational excitation can be approximated with one thermal (~700 K) component representative of an average gas temperature, and one nonthermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model of the Orion Bar PDR, and find that the predicted excitation matches the data qualitatively, while adjustments to the parameters of the PDR model are required to reproduce the intensity of the 0–0 S (6) to S (8) lines.

SummaryCeres is the largest object in the Solar System main belt. Clearly, Ceres experienced extensive water-related processes and geochemical differentiation and nowadays it is a body with a complex geological and chemical history [1]. Its surface is characterized by dark materials, phyllosilicates, ammonium-bearing minerals, carbonates, water ice, and salts. In addition to a global presence of carbon bearing chemistry, local concentration of aliphatic organics has been detected by Dawn [2].In this context, we have started a series of laboratory spectroscopy measurements targeted to study the physicochemical interactions between organic material and minerals possibly present on Ceres. The goal is to understand the transformations induced on these samples by ultraviolet radiation, neutral atoms, and fast ions, under experimental conditions that simulate the environment of Ceres. The spectroscopic data obtained in laboratory experiments allow, through the comparison with the observations of the VIR spectrometer aboard the Dawn mission, to clarify the nature and origin of organic material identified on Ceres. IntroductionOrganic material in the minor bodies of the Solar System is an important component to understand planetary evolution and, eventually, the origin of life. Nevertheless, our knowledge on the subject is still limited. Recently the Dawn mission, thanks to the data collected by the Italian instrument VIR [3], showed clear evidence of a high amount of aliphatic organic material on the surface of Ceres [4, 5, 6] (Fig 1). This evidence has raised new questions about the origin and preservation of this material, especially when considering its high estimated abundance and the mineralogical context. Fig 1 Ceres spectra of the organic-rich area in Ernutet crater (label “Organics”); of a background organic-poor area from a region southeast of Ernutet (label “Background”); and of Occator bright material (label “Carbonate”) [4]. In order to understand the organic chemical species and in particular their abundance on Ceres, laboratory studies were performed [7]. The importance of having a direct comparison between laboratory and remote sensing data can provide a further investigation clues to shed light on the origin and evolution of Ceres. Through this project, we intend to study, through dedicated experiments, the interaction between minerals, water, and organic concerning the environmental conditions of Ceres. Making a synergistic use of complementary and indispensable skills present within INAF (Italian National Institute of Astrophysics) laboratories we investigated a complex issue such as that concerning the origin and preservation of organic molecules on planetary surfaces. Within INAF, complementary and unique realities coexist which, thanks to joint and coordinated work, can give a new interpretation of the physical-chemical processes active on Ceres.Project development and resultsIn this study, we prepare mixtures of materials resembling the Ceres surface composition [8, 9] adding organic molecules in order to:(i) understand how organic molecules behave and eventually degrade on Ceres, in particular, how aliphatic molecules degrade by energetic processing with fast ions (keV-MeV) and UV photons [10, 11]. Moreover, the physico-chemical properties of the materials exposed to a flux of neutral atoms are investigated [12, 13].(ii) evaluate the interaction between ammoniated minerals and simple organic molecules that may lead to the synthesis of complex compounds. In the presence of ultraviolet (UV) radiation, these minerals present on the surface of Ceres can show photocatalytic effects accelerating the photo-reactions, which generally destroy the original organic molecule and in the synthesis of new complex organic molecules [14].(iii) evaluate the role of minerals in the protection or degradation of organic compounds. Some studies indicated a fundamental role of clays in the catalysis and preservation of organic materials [15]. Ceres is rich in clays and other hydrated minerals, making the interactions with the observed organics of particular interest.The project is carried out by several INAF institutes and laboratories. In detail: INAF-IAPS Istituto di Astrofisica e Planetologia Spaziali prepared the analog mineral mixtures taking into account the compositional information gained by VIR observations. INAF - Osservatorio Astrofisico di Arcetri subsequently doped the mixture with several organic investigating UV photostability in Ceres analog conditions and the influence of temperature. INAF -Osservatorio Astronomico di Capodimonte studied irradiation with atoms and temperature effect while INAF - Osservatorio Astrofisico di Catania performed irradiation with fast ions. Finally, results of laboratory measurements were compared with data obtained by VIR instrument onboard Dawn mission.AcknowledgementsThis work is support by INAF Main Stream programme, grant 1.05.01.86.08 Evoluzione ed alterazione del materiale organico su Cerere (ref. Maria Cristina De Sanctis).References[1] De Sanctis et al., 2016, Nature 536, 54–57[2] Marchi et al., Nature Astr., 2019[3] De Sanctis et al., 2011, Space Science Reviews 163, 329-369.[4] De Sanctis et al., science 2017 355, 719[5] Pieters et al., 2018, Meteoritics and Planetary Science 53 (9), 1983-1998[6] De Sanctis et al., 2019, 482 (2), 2407–2421[7] Vinogradoff et al., 2021[8] Ferrari et al., 2019, Icarus 321, 522-530[9]De Angelis et al., 2021 JGR Planets doi: 10.1029/2020JE006696[10] Baratta et al. 2002, A&A, 384, 343-349[11] Brucato et al. 2006, A&A, 455, 395-399[12] Mennella et al. 2003, ApJ, 587, 727-738[13] Palumbo et al 2004, Ad. Sp. Res., 33, 49-56[14] Fornaro et al. 2013, Icarus, 226(1), 1068–1085[15] Fornaro et al 2018, Astrobiology, 18, 989-1007

This work focuses on the ice features toward the binary protostellar system Ced 110 IRS 4A and 4B, and observed with JWST as part of the Early Release Science Ice Age collaboration. We aim to explore the JWST observations of the binary protostellar system Ced 110 IRS4A and IRS4B to unveil and quantify the ice inventories toward these sources. We compare the ice abundances with those found for the same molecular cloud. The analysis is performed by fitting or comparing laboratory infrared spectra of ices to the observations. Spectral fits are carried out with the ENIIGMA fitting tool that searches for the best fit. For Ced 110 IRS4B, we detected the major ice species H_2O, CO, CO_2 and NH_3. All species are found in a mixture except for CO and CO_2, which have both mixed and pure ice components. In the case of Ced 110 IRS4A, we detected the same major species as in Ced 110 IRS4B, as well as the following minor species CH_4, SO_2, CH_3OH, OCN^-, NH_4^+ and HCOOH. Tentative detection of N_2O ice (7.75 μm), forsterite dust (11.2 μm) and CH_3^+ gas emission (7.18 μm) in the primary source are also presented. Compared with the two lines of sight toward background stars in the Chameleon I molecular cloud, the protostar has similar ice abundances, except in the case of the ions that are higher in IRS4A. The clearest differences are the absence of the 7.2 and 7.4 μm absorption features due to HCOO^- and icy complex organic molecules in IRS4A and evidence of thermal processing in both IRS4A and IRS4B as probed by the CO_2 ice features. We conclude that the binary protostellar system Ced 110 IRS4A and IRS4B has a large inventory of icy species. The similar ice abundances in comparison to the starless regions in the same molecular cloud suggest that the chemical conditions of the protostar were set at earlier stages in the molecular cloud.

Volatile organic molecules and a complex organic refractory material were detected on the Moon and on lunar samples. The Moon’s surface is exposed to a continuous flux of solar UV photons and fast ions, e.g. galactic cosmic rays (GCRs), solar wind (SW), and solar energetic particles (SEPs), that modify the physical and chemical properties of surface materials, thus challenging the survival of organic compounds. With this in mind, the aim of this work is to estimate the lifetime of organic compounds on the Moon’s surface under processing by energetic particles. We performed laboratory experiments to measure the destruction cross section of selected organic compounds, namely methane (CH4), formamide (NH2CHO), and an organic refractory residue, under simulated Moon conditions. Volatile species were deposited at low temperature (17 - 18 K) and irradiated with energetic ions (200 keV) in an ultra-high vacuum chamber. The organic refractory residue was produced after warming up of a CO:CH4 ice mixture irradiated with 200 keV H+ at 18 K. All the samples were analyzed in situ by infrared transmission spectroscopy. We found that destruction cross sections are strongly affected (up to one order of magnitude) by the dilution of a given organic in an inert matrix. Among the selected samples, organic refractory residues are the most resistant to radiation. We estimated the lifetime of organic compounds on the surface of the Moon by calculating the dose rate due to GCRs and SEPs at the Moon’s orbit and by using the experimental cross section values. Taking into account impact gardening, we also estimated the fraction of surviving organic material as a function of depth. Our results are compatible with the detection of CH4 in the LCROSS eject plume originating from layers deeper than about 0.7 m at the Moon’s South Pole and with the identification of complex organic material in lunar samples collected by Apollo 17 mission.

One of the main problems in astrochemistry is determining the amount of sulfur in volatiles and refractories in the interstellar medium. The detection of the main sulfur reservoirs (icy H$_2$S and atomic gas) has been challenging, and estimates are based on the reliability of models to account for the abundances of species containing less than 1% of the total sulfur. The high sensitivity of the James Webb Space Telescope provides an unprecedented opportunity to estimate the sulfur abundance through the observation of the [S I] 25.249 $\mu$m line. We used the [S III] 18.7 $\mu$m, [S IV] 10.5 $\mu$m, and [S l] 25.249 $\mu$m lines to estimate the amount of sulfur in the ionized and molecular gas along the Orion Bar. For the theoretical part, we used an upgraded version of the Meudon photodissociation region (PDR) code to model the observations. New inelastic collision rates of neutral atomic sulfur with ortho- and para- molecular hydrogen were calculated to predict the line intensities. The [S III] 18.7 $\mu$m and [S IV] 10.5 $\mu$m lines are detected over the imaged region with a shallow increase (by a factor of 4) toward the HII region. We estimate a moderate sulfur depletion, by a factor of $\sim$2, in the ionized gas. The corrugated interface between the molecular and atomic phases gives rise to several edge-on dissociation fronts we refer to as DF1, DF2, and DF3. The [S l] 25.249 $\mu$m line is only detected toward DF2 and DF3, the dissociation fronts located farthest from the HII region. The detailed modeling of DF3 using the Meudon PDR code shows that the emission of the [S l] 25.249 $\mu$m line is coming from warm ($>$ 40 K) molecular gas located at A$_{\rm V}$ $\sim$ 1$-$5 mag from the ionization front. Moreover, the intensity of the [S l] 25.249 $\mu$m line is only accounted for if we assume the presence of undepleted sulfur.

Mid-infrared emission features probe the properties of ionized gas, and hot or warm molecular gas. The Orion Bar is a frequently studied photodissociation region (PDR) containing large amounts of gas under these conditions, and was observed with the MIRI IFU aboard JWST as part of the "PDRs4All" program. The resulting IR spectroscopic images of high angular resolution (0.2") reveal a rich observational inventory of mid-IR emission lines, and spatially resolve the substructure of the PDR, with a mosaic cutting perpendicularly across the ionization front and three dissociation fronts. We extracted five spectra that represent the ionized, atomic, and molecular gas layers, and measured the most prominent gas emission lines. An initial analysis summarizes the physical conditions of the gas and the potential of these data. We identified around 100 lines, report an additional 18 lines that remain unidentified, and measured the line intensities and central wavelengths. The H I recombination lines originating from the ionized gas layer bordering the PDR, have intensity ratios that are well matched by emissivity coefficients from H recombination theory, but deviate up to 10% due contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni, and show how certain line ratios vary between the five regions. We observe the pure-rotational H$_2$ lines in the vibrational ground state from 0-0 S(1) to 0-0 S(8), and in the first vibrationally excited state from 1-1 S(5) to 1-1 S(9). We derive H$_2$ excitation diagrams, and approximate the excitation with one thermal (~700 K) component representative of an average gas temperature, and one non-thermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model for the Orion Bar PDR and highlight the differences with the observations.

The JWST has captured the most detailed and sharpest infrared images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR). We investigate the fundamental interaction of far-ultraviolet photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments. Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of 0.1-1" (0.0002-0.002 pc or 40-400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. A complex, structured, and folded DF surface was traced by the H2 lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate.

IntroductionThe study on the composition of meteorites, asteroids, comets, and trans-neptunian objects suggest that they contain materials originated during the early stages of the solar system formation. A relevant fraction of organic materials trapped in small bodies are thought to form from chemical reactions that involve carbon-bearing frozen volatiles species that are revealed in various star-forming regions and protoplanetary disks [1, 2]. Complex reactions are triggered by the interaction of solid-phase materials with energetic charged particles, such as galactic cosmic-rays (GCR), and energetic photons (x-rays, UV) that induce both the destruction of the pristine species and the formation of new compounds [3]. In addition, solar wind (SW) and solar energetic particles (SEP) also induce chemical reactions at the surface of outer icy small bodies [4]. As a result, pristine volatile species are destroyed and more complex molecules can form. The chemical complexity is further increased by the thermal processing that matter can suffer both during the star-formation process and in the event of migrations in the inner solar system. Processing at high temperature also affects the properties of meteorites during their entry into the atmosphere. Understanding how this event affects the physical, chemical, and spectral properties of meteorites is of particular relevance because these samples are often used to interpret the spectra of asteroids and other small bodies. Information on the chemistry triggered by energetic charged particles and heating in the formation of organic matter comes from laboratory experiments where simple carbon-bearing molecules are deposited at very low temperature (≤ 20 K), exposed to ion beams (keV-MeV), and further heated to room temperature (~ 300 K). These experiments lead to the formation of the so-called organic refractory residues, samples whose characterization revealed the presence of thousands of organic species, including compounds of astrobiological relevance, providing insights into the composition of extraterrestrial organics [5, 6, 7]. However, no information is available on the heating of organic refractory residues at temperatures higher than 300 K. MethodsWe present new experiments of ion bombardment and further thermal heating of simple frozen volatile compounds representative of the pristine composition of icy materials in the presolar cloud. Ion bombardment experiments were performed with the facilities available at the Laboratory for Experimental Astrophysics (LASp) at INAF-Osservatorio Astrofisico di Catania (Italy). Ice mixtures containing H2O, CH3OH, NH3 and CO, CH4, and N2 were deposited in a ultra-high vacuum chamber (P ≤10-8 mbar) at low temperature (18 K) and exposed to 200 keV H+ and He+, respectively. After the bombardment, processed ices were warmed-up to 300 K with a constant heating rate in order to produce organic refractory residues. These samples were then extracted from the UHV chamber, stored in vacuum sample holders and transferred to the Planetary Spectroscopy Laboratory (PSL) at the DLR Berlin. At the PSL, organic refractory residues were placed in a oven and heated in vacuum (P≤10-2 mbar) up to 970 K. The heating was performed in various step and with a constant heating rate.During the ion bombardment, samples were analysed by means of Fourier-transform infrared (FT-IR) spectroscopy in the near- and mid-IR (1.25-10.5 µm, 8000-950 cm-1) in transmittance mode. Several spectra were acquired in-situ during the processing, allowing us to follow the changes induced by energetic charged particles in the composition of ices. Spectra were also acquired during the warm-up to 300 K to follow the formation of organic refractory residues. At the PSL, FT-IR spectroscopy was also used to characterize samples after each step of warm-up.ResultsThe spectra collected during ion bombardment at 18 K show the destruction of the pristine frozen compounds and the formation of new species, including the precursors of complex organic species, such as aldehydes (5.81 µm, 1720 cm-1) and CN-bearing compounds (4.42 µm, 2260 cm-1). The characterization performed after ion bombardment and during warm-up to 300 K show the sublimation of the most volatile species and spectral changes that point to the formation of organic refractory materials, as reported in previous similar experiments [8]. The further heating performed at the DLR shows relevant changes in the spectral properties of samples. In all cases, we observed a decrease in the intensity of the signal that is associated to a loss of material during warm-up. Shifts in the band position and changes in the relative intensity of absorption features also testify the alteration of the chemical properties of samples. In particular, we reveal strong changes in the 5.8-6.8 µm (1720-1470 cm-1) region that includes the absorption features of C=C, C=O, and C=N bearing compounds as well as in the region around 4.5 µm (2200 cm-1) that contains the absorption features of nitriles.The data obtained are used to interpret the IR spectra of organic-rich meteorites and will support the understanding of the alteration induced by thermal processing of organic-rich surfaces in the inner solar system. AcknowledgementsThis work is supported by the Istituto Nazionale di Astrofisica (INAF) through the grant Organic Refractories Sustaining microOrganisms - ORSO, CUP C63C23001250005. RGU acknowledges the support from the Società Italiana di Scienze Planetarie - Angioletta Coradini (SISP-AC).References[1] McClure, M. K., Rocha, W. R. M., Pontoppidan, K. M. et al. 2023, Nat. Astronomy, 7, 431[2] Sturm, A. J., McClure, M. K., Beck, T. L. et al. 2023, A&A, 679, A138[3] Rothard, H., Domaracka, A., Boduch, P., et al. 2017, J. Phys. B, 50, 062011[4] Urso, R. G., Vuitton, V., Danger, G. et al. 2020, A&A, 644, A115[5] Nuevo, M., Auger, G., Blanot, D., & D’Hendecourt, L. 2008, Orig. Life Evol. Biosph., 38, 37[6] Meinert, C., Myrgorodska, I., de Marcellus, P., et al. 2016, Science, 352, 208[7] Danger, G., Orthous-Daunay, F. R., de Marcellus, P., et al. 2013, Geochim. Cosmochim. Acta, 118, 184[8] Baratta, G. A., Chaput, D., Cottin, H., et al. 2015, Planet. Space Sci., 118, 2

(Abridged) We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR (crossing the ionisation front (IF)), and the subsequent transition to the molecular PDR (crossing the dissociation front (DF)). We use high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science Program. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. We observe numerous smaller scale structures whose typical size decreases with distance from Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures consistent with the hot irradiated surface of small-scale dense clumps deep inside the PDR. The H2 lines reveal multiple, prominent filaments which exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star- and planet formation as well as galaxy evolution.

Ceres hosts notable aliphatic-organic concentrations, ranging from approximately 5 to >30 weight % in specific surface areas. The origins and persistence of these organics are under debate due to the intense aliphatic organic signature and radiation levels in Ceres’ orbit, which would typically lead to their destruction, hindering detection. To investigate this, we conducted laboratory experiments to replicate how the signature of the organic-rich regions would degrade due to radiation. Our findings indicate a fast degradation rate, implying the exposure of buried organics within the past few million years. This degradation rate, coupled with observed quantities, implies that the aliphatics must be present in substantial quantities within the shallow subsurface. Our estimates suggest an initial aliphatic abundance 2 to 30 times greater than currently observed, surpassing significantly the levels found in carbonaceous chondrites, indicating either a significant concentration or remarkable purity.

Ascertaining the morphology and composition of the icy mantles covering dust grains in dense, cold regions of the interstellar medium is essential to developing accurate astrochemical models, determining conditions for ice formation, constraining chemical interactions in and on icy grains and understanding how ices withstand space radiation. The widely observed infrared spectroscopic signature of H2O ice at similar to 3 mu m discriminates crystalline from amorphous structures in interstellar ices. Weaker bands seen only in laboratory ice spectra at similar to 2.7 mu m, termed 'dangling OH' (dOH), are attributed to water molecules not fully bound to neighbouring water molecules and are often considered as tracing the degree of ice compaction. We exploit the high sensitivity of JWST NIRCam to detect two dOH features at 2.703 and 2.753 mu m along multiple lines of sight probing the dense cloud Chamaeleon I, attributing these signatures to unbound dOH in cold water ice and dOH in interaction with other molecular species. These detections open a path to using the dOH features as tracers of the formation, composition, morphology and evolution of icy grains during the star and planet formation process.