The desorption of volatile molecules from dust grains in cold dense clouds is crucial for the chemical inventory in the various stages of cloud collapse. In this work we investigate the desorption of N2, CO, CH4 and CO2 from surfaces of hydrogenated amorphous carbon (HAC), which, according to IR observations, is one of the main components of interstellar dust.

Implementation of a novel experimental approach using a bright source of narrowband x-ray emission has enabled the production of a photoionized argon plasma of relevance to astrophysical modelling codes such as Cloudy. We present results showing that the photoionization parameter ζ = 4πF/ne generated using the VULCAN laser was ≈ 50 erg cm s−1, higher than those obtained previously with more powerful facilities. Comparison of our argon emission-line spectra in the 4.15 - 4.25 Å range at varying initial gas pressures with predictions from the Cloudy code and a simple time-dependent code are also presented. Finally we briefly discuss how this proof-of-principle experiment may be scaled to larger facilities such as ORION to produce the closest laboratory analogue to a photoionized plasma.

In dense interstellar clouds that are shielded from high-energy radiation (e.g., UV photons or cosmic rays), H-atom addition and abstraction reactions that take place on grain surfaces play principal roles in the synthesis or decomposition of complex organic molecules (COMs). These reactions are extensively investigated with laboratory experiments by bombarding astrophysical analogue ices with a beam of low-temperature H atoms. Here we demonstrate that, although 2-4 K solid para-H2 does not represent a typical environment of the surface of interstellar grains, para-H2 matrix isolation combined with IR spectroscopy is a complementary tool to sensitively detect astrochemical hydrogenation and dehydrogenation processes.

Saturn’s moon Titan was explored by the Cassini mission for nearly 13 years. Important discoveries made during the Cassini mission include the observations of stratospheric clouds in Titan’s cold polar regions in which spectral features or organic molecules were detected in the infrared (<100 μm). In particular, benzene (C6H6) ice spectral signatures were recently detected at unexpectedly high altitudes over the South Pole. The combined experimental, modeling and observational effort presented here has been devised and executed in order to interpret these high altitude benzene observations. Our multi-disciplinary approach aims to understand and characterize the microphysics of benzene clouds in Titan’s South Pole.

While gas-phase reactions and surface reactions on bare carbonaceous or siliceous dust grains contribute to cosmic chemistry, the energetic processing of cosmic ices via photochemistry and radiation chemistry is thought to be the dominant mechanism for the cosmic synthesis of prebiotic molecules. Because most previous laboratory astrochemical studies have used light sources that produce >10 eV photons and are, therefore, capable of ionizing cosmic ice analogs, discerning the role of photochemistry vs. radiation chemistry in astrochemistry is challenging. By using a source whose photon energy does not exceed 8 eV, we have studied ammonia and methanol cosmic ice reactions attributable solely to photochemistry. We compare these results to those obtained in the same ultrahigh vacuum chamber with 1 keV electrons which instead initiate radiation chemistry in cosmic ice analogs.

HD 66051 is an eclipsing and spectroscopic double-lined binary (SB2), hosting two chemically peculiar stars: a highly peculiar B star as primary and an Am star as secondary. The investigation of the new high-resolution UVES spectrum of HD 66051 allowed us to decide on the chemical peculiarity type of both components with more reliability. An analysis of TESS photometric time series data will further specify the physical parameters of the stars and the orbital parameters of the system.

By virtue of the physical, chemical and dynamical characteristics of asteroids, researchers gain insight into the formation and evolution of our Solar system. Since these objects do not undergo any changes, or the changes during the Solar system evolution are insignificant, we are certain they carry important information regarding the formation of our planetary system and its evolution. Knowing the spectral class of an asteroid is crucial for determining its chemical properties. In our work the spectral classification was done on several asteroids by comparing their spectra with laboratory spectra. We determined spectral types of the asteroids by the overall shapes of the spectra between 450 nm and 700 nm. Increasing the number of asteroids with known rotation period, shapes and spectra enriches the asteroid database of physical and dynamical characteristics of asteroid population.

We present results of full general relativistic (GR), three-dimensional (3D) core-collapse simulation of a massive star with multi-energy neutrino transport. Using a 70Mȯ zero-metallicity star, we show that the black-hole (BH) formation occurs at ∼ 300 ms after bounce. At a few ∼ 10 ms before the BH formation, we find that the stalled bounce shock is revived by neutrino heating from the forming hot proto-neutron star (PNS), which is aided by vigorous convection behind the shock. Our numerical results present the first evidence to validate the BH formation by the so-called fallback scenario. Furthermore we present results from a rapidly rotating core-collapse model of a 27Mȯ star that is trending towards an explosion. We point out that the correlated neutrino and gravitational-wave signatures, if detected, could provide a smoking-gun evidence of rapid rotation of the newly-born PNS.

We propose a role for CO ice mantles in ion recombination reactions, and demonstrate how the subsequent fall in the degree of gas phase ionization decreases the time required for cloud collapse under gravity by a factor of 5-6. Experimental results demonstrate that CO films prepared at cryo-temperatures spontaneously harbour electric fields immediately upon growth. Using what is known from observations about prestellar cloud conditions in the ISM, we explain how this phenomenon can lead to an acceleration in ion recombination reaction rates. The result is a pathway for cloud collapse to occur before cloud disruption by supernova remnants.

Understanding the physical structure of the planet formation environment, the protoplanetary disk, is essential for the interpretation of high resolution observations of the dust and future observations of the magnetic field structure. Observations of multiple transitions of molecular species offers a unique view of the underlying physical structure through excitation analyses. Here we describe a new method to extract high-resolution spectra from low-resolution observations, then provide two case studies of how molecular excitation analyses were used to constrain the physical structure in TW Hya, the closest protoplanetary disk to Earth.

The role of H2 in forming interstellar complex organics is still not clear due to the high activation energies required for “non-energetic” association reactions. In this work, we investigated the potential contribution of H2 to the hydrogenated species (HnNCO) formation on dust grains when the “energetic” processing is involved. The goal is to test whether an additional hydrogenation pathway is possible upon UV irradiation of a CO:H2 ice mixture. It is proposed that the electronically excited carbon monoxide (CO*) induced by UV-photons can react with a ground-state H2 to form HCO, ultimately enhancing the production of COMs in ice mantle.

The outflows of asymptotic giant branch (AGB) stars are important astrochemical laboratories, rich in molecular material and host to various chemical processes, including dust formation. Since the different chemistries are relatively easily probed, AGB outflows are ideal testbeds within the wider astrochemical community. Recent observations are pushing the limits of both our current chemical models and radiative transfer routines. Current chemical models are restricted by the completeness of their chemical networks and the accuracy of the reaction rates. The molecular abundances retrieved by radiative transfer routines are strongly dependent on collisional rates, which are often not measured or calculated for molecules of interest. To further our understanding of the chemistry within the outflow, collaboration with the laboratory astrophysics community is essential. This collaboration is mutually beneficial, as it in turn provides new science questions for laboratory experiments and computations.

The properties of interstellar dust (ID) can be studied in great detail by making use of X-ray spectroscopy techniques. The radiation of X-rays sources is scattered and absorbed by dust grains in the interstellar medium. The X-ray band is especially suitable to study silicates - one of the main components of ID -since it contains the absorption edges of Si, Mg, O and Fe. In the Galaxy, we can use absorption features in the spectra of X-ray binaries to study the size distribution, composition and crystalline structure of grains. In order to derive these properties, it is necessary to acquire a database of detailed extinction cross sections models, that reflects the composition of the dust in the interstellar medium. We present the extinction profiles of a set of newly acquired measurements of 14 dust analogues at the Soleil Synchrotron facility in Paris, where we focus on silicates and the Si-K edge in particular, which is modelled with unprecedented accuracy. These models are used to analyse ID in the dense environments of the Galaxy.

We present a new experimental setup called AROMA (The Aromatic Research of Organics with Molecular Analyzer) based on the use of laser mass spectrometry techniques. We demonstrate the potential of AROMA for the analysis of meteoritic samples and cosmic dust analogues. Tens of peaks are identified in the mass spectra with notable discrepancies across the different samples. These discrepancies provide clues on the chemical history of each sample and are not a bias of our analysis. A double bound-equivalent (DBE) method is applied to sort the detected carbonaceous molecules into families of compounds. It reveals in addition of polycyclic aromatic hydrocarbons, the presence of other populations such as mixed aromatic-aliphatic species and carbon clusters.

The Sun's atmosphere increases in temperature from 6000 degrees at the surface to over a million degrees at heights of a few thousand kilometers. This surprising temperature increase is still an active area of scientific study, but is generally thought to be driven by the dynamics of the Sun's magnetic field. The combination of a 2-to-3 order of magnitude temperature range and a low plasma density makes the solar atmosphere perhaps the best natural laboratory for the study of ionized atoms. Atomic transitions at ultraviolet (UV) and X-ray wavelength regions generally show no optical depth effects, and the lines are not subject to the interstellar absorption that affects astronomical sources. Here I highlight the importance of atomic data to modeling UV and X-ray solar spectra, with a particular focus on the CHIANTI atomic database. Atomic data needs and problems are discussed and future solar mission concepts presented.

The emergence of life on Earth may have its origin in organic molecules formed in the interstellar medium. Molecules with amide and isocyanate groups resemble structures found in peptides and nucleobases and are necessary for their formation. Their formation is expected to take place in the solid state, on icy dust grains, and is studied here by far-UV irradiating a CH4:HNCO mixture at 20 K in the laboratory. Reaction products are detected by means of infrared spectroscopy and temperature programmed desorption - mass spectrometry. Various simple amides and isocyanates are formed, showing the importance of ice chemistry for their interstellar formation. Constrained by experimental conditions, a reaction network is derived, showing possible formation pathways of these species under interstellar conditions.

The laboratories at the Centre for Astrochemical Studies at the Max Planck Institute for Extraterrestrial Physics are devoted to spectroscopic studies of molecules of astrophysical relevance. In particular, in this paper we report on the two experiments that can produce and probe unstable molecules, like radicals and ions.

PAH clusters are one candidate species for the interstellar “very small grains” or “VSGs”, i.e., dust grains small enough to be stochastically heated and contribute to the aromatic infrared emission bands (AIBs). This possibility motivated laboratory experiments on the infrared spectroscopy of PAH clusters using matrix isolation spectroscopy. The spectral shifts due to PAH clustering in argon matrices provide clues for the AIB contribution from PAH clusters in the interstellar medium. Here we review results from a number of small PAH species, extrapolation to the much larger PAHs believed to be present in the interstellar medium, and the implications for a PAH cluster contribution to the VSG population.

Using a cold plasma reactor in which we inject an organosilicon molecular precursor, we investigate chemical mechanisms that can be involved in dust formation in evolved stars. By injecting metal atoms into the gas-phase, we investigate the role of metals on dust composition. We show the formation of composite particles made of pure metal (silver) nanoparticles embedded in an organosilicon dust. We study the impact of oxygen and show that it can inhibit dust formation, likely through the destruction of nucleation seeds.

The recent calculations of atomic data for ions of astrophysical interest are reviewed with a focus on work performed in Cambridge. The calculations have been benchmarked against high-resolution laboratory and astrophysical spectra. A framework for assessing uncertainties in atomic data has also been developed. Long-standing discrepancies in predicted spectral line intensities have been resolved, and a significant number of levels in coronal ions have finally been identified, improving the modelling of the extreme-ultraviolet and soft X-ray spectral regions. Recent improvements based on collisional-radiative modelling are presented. They are relevant for the modelling of satellite lines in the X-rays and for solving the long-standing problems in the chromosphere-corona transition in stellar atmospheres.