We report new laboratory measurements of atomic oscillator strengths (log gfs) for stellar atmosphere models.

Modern experimental techniques, including LIF lifetime and FTS branching fraction measurements, have increased the reliability of atomic transition probabilities in the UV and visible. However, this combination is problematic in the increasingly important IR region, resulting in a significant gap between the capabilities to record new astronomical spectra and the data needed to sufficiently analyze them. To aid in closing this gap, we are incorporating alternative techniques to measure sets of Fe-group oscillator strengths in the near-IR.

We summarize measurements of improved wavelengths of Fe V and Ni V in the vacuum ultraviolet.

We summarize our analysis of singly-ionized elements of astrophysical interest.

We report new measurements of atomic data for the neutral, singly and doubly ionised iron group element spectra for modern astrophysics applications.

We present an overview of the advances made during the past 15 years by the Atomic Physics and Astrophysics Group of Mons University regarding the analysis of the spectra, the transition probabilities, and the radiative lifetimes in heavy elements. More precisely, this review is focused on neutral and lowly ionized atoms belonging to the lanthanide group, the fifth row, and the sixth row of the periodic table (Z = 37–86), for which a very large amount of new data has been obtained.

We carried out a systematic study of the electronic structure of doubly-ionized Fe-peak species, from Sc III to Ni III. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) method and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in the AUTOSTRUCTURE code. This multi-platform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data.

We present the first experimentally determined oscillator strengths for the Pb ii transitions at 1203.6 Å and 1433.9 Å, obtained from lifetime measurements made using beam-foil techniques. We also present new detections of these lines in the interstellar medium from an analysis of archival spectra acquired by the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. Our observations of the Pb ii λ1203 line represent the first detection of this transition in interstellar gas. Our experimental f-values for the Pb ii λ1203 and λ1433 transitions are consistent with recent theoretical results, including our own relativistic calculations, but are significantly smaller than previous values based on older calculations. Our new f-value for Pb ii λ1433 (0.321 ± 0.034) yields an increase in the interstellar abundance of Pb of 0.43 dex over estimates based on the f-value listed by Morton. With our revised f-values, and with our new detections of Pb ii λ1203 and λ1433, we find that the depletion of Pb onto interstellar grains is not nearly as severe as previously thought, and is very similar to the depletions seen for elements such as Zn and Sn, which have similar condensation temperatures.

The photochemistry of CO and its isotoplogues affects the structure and evolution of many astronomical environments, including interstellar clouds, circumstellar disks around newly formed stars, and the envelopes surrounding highly evolved stars. When in the presence of a strong ultraviolet field, the primary destruction mechanism for interstellar and circumstellar CO is photodissociation, which is entirely governed by discrete line absorption into predissociating levels in the wavelength range 91.2 to 111.8 nm. Because the CO spectrum consists primarily of resolved line features, self-shielding effects in high-column density environments can lead to strong isotopic fractionation signatures in both CO and elemental oxygen and carbon; for example, CO self-shielding in the solar nebula has been invoked to explain the unusual oxygen isotope ratios observed in the earliest solar system condensates, viz. calcium-aluminum inclusions (CAIs) in primitive meteorites.

We will identify new molecules in the interstellar medium by comparing a catalog of theoretical spectra generated by the NASA Ames quantum chemistry group with recent high-resolution astronomical line surveys.

Highly accurate IR line lists are ready for 13 CO2 isotopologues and 7 SO2 isotopologues. Ames-296K IR lists carry 0.01 - 0.03 cm−1 accuracy up to 13,000 cm−1 for CO2 and 5500 cm−1 for SO2, and 90–95% intensity agreement for most observable bands. Good for atmospheric modeling on Venus and Exoplanets.

Polycyclic aromatic hydrocarbons (PAHs) are considered as plausible carriers for the extended red emission (ERE), a photoluminescent process associated with a wide variety of interstellar environments, as well as for broad emission band features seen in cometary spectra. We report the absorption spectra of phenanthrene, anthracene, fluoranthene, pentacene, pyrene, chrysene and triphenylene isolated at 10 K in solid argon matrices together with laser induced fluorescence (LIF) spectra at 355 nm of matrix-isolated anthracene and fluoranthene. LIF spectra are compared with the UV/blue fluorescence spectra of the Red Rectangle Nebula (RR). The LIF spectra measured in solid Ar matrices have been shifted to the predicted position of the PAH band emission in the gas phase for comparison with the astronomical observations (Fig. 1).

Polycyclic aromatic hydrocarbons (PAHs) are one of the most interesting components of the interstellar medium (ISM). But different from laboratory - the isolation of a single species is not possible. The spectra contain a superposition of many different molecules. Therefore a sophisticated understanding of all possible subtypes is required. We present an investigation of the IR spectra of PAHs containing (5, 7)-member ring defects. Using density functional theory, the influence of those defects on the IR spectra of coronene (C24H12) and pyrene (C16H10) and their cations and anions were examined in detail. Additionally, the potential energy surface of the neutral species is explored and an alternative formation pathway is taken into account.

We discuss the capabilities of the laboratory facility, COSmIC, that was developed to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory

Interstellar methanol is thought to be the precursor of larger, more complex organic molecules. It holds a central role in many astrochemical models (e.g., Garrod & Herbst 2006). Methanol has also been the focus of several laboratory studies (e.g., Watanabe et al. 2004, Fuchs et al. 2009), in an effort to gain insight into grain-surface chemistry, which potentially builds chemical complexity already in the cold, dark prestellar phase. The case of methanol is a prime example of experimental work having implications on astronomical scales. Drozdovskaya et al. (2014) unified physical and chemical models to simulate infalling material during the birth of a low-mass protostar. An axisymmetric 2D semi-analytic collapse model (Visser et al. 2009), wavelength-dependent radiative transfer calculations with RADMC3D (Dullemond & Dominik 2004) and a comprehensive gas-grain chemical network (Walsh et al. 2014) were used to study two modes of protoplanetary disk formation.

Amorphous solid water (ASW) is of great importance in astrochemistry as it has been detected in star forming regions, comets, and cold solar-system objects. A key property of ASW is its porous nature (with the extent of porosity reflecting the formation and growth conditions) and the subsequent pore collapse when the ice is heated. If interstellar ices are porous there are huge implications to both the process of planet formation and the budgets of molecular gas in the solid and gas phases. It is therefore vital to understand ASW porosity over astronomically relevant conditions in order to effectively model its potential effects on these processes.

Jupiter-sized brown dwarfs are found in the solar neighborhood with effective temperature Teff as low as 250 K [1]. Iron, silicates, chlorides and sulfides condense in the atmospheres of the Teff ≈ 2000 K L-type and Teff ≈ 1000 K T-type dwarfs [2]. At the T-/Y-type boundary, Teff ≈ 500 K and atmospheres are clear [3]. The next species to condense are H2O at Teff ≈ 350 K and NH3 at Teff ≈ 200 K [4].

Observations show that emission from the Unidentified Infrared (UIR) bands is strongly suppressed in H II regions. UIR bands are generally attributed to vibrational relaxation of FUV - excited Polycyclic Aromatic Hydrocarbon (PAH) molecules or hydrocarbon nanoparticles containing aromatic domains. If the strongly reduced UIR emission in H II regions is due to the suppression of the carriers, an efficient destruction mechanism is required to explain observations. The aim of this work is to clarify whether UV processing of PAHs and nanoparticles is indeed responsible for the observed lack of infrared emission. We present here our first results on the physical response to photo-processing of the proposed UIR-bands carriers.

Polarimetric astronomical observations on dust clouds and regolithic surfaces require laboratory simulations on samples to provide clues to properties of the scattering media. Similarly, in-situ radar investigations of Solar System bodies require laboratory studies to infer the physical properties of their interiors. Recent developments are illustrated by analyses of comet 67P/Churyumov-Gerasimeko (C-G) remote observations and in-situ studies from Rosetta mission.

Submillimetre observations of the externally irradiated protostar R CrA IRS7B show that this source has dramatically different chemical abundances in comparison with otherwise similar embedded protostars not subject to external irradiation.