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Context. Interstellar dust particles, in particular carbonaceous nano-grains (like polycyclic aromatic hydrocarbons, fullerenes, and amorphous hydrogenated carbon), are critical players for the composition, energy budget, and dynamics of the interstellar medium (ISM). The dust properties, specifically the composition and size of dust grains are not static; instead, they exhibit considerable evolution triggered by variations in local physical conditions such as the density and gas temperature within the ISM, as is the case in photon-dominated regions (PDRs). The evolution of dust and its impact on the local physical and chemical conditions is thus a key question for understanding the first stages of star formation. Aims. From the extensive spectral and imaging data of the JWST PDRs4All program, we study the emission of dust grains within the Orion Bar – a well-known, highly far-UV (FUV)-irradiated PDR situated at the intersection between cold, dense molecular clouds, and warm ionized regions. The Orion Bar because of its edge-on geometry provides an exceptional benchmark for characterizing dust evolution and the associated driving processes under varying physical conditions. Our goal is to constrain the local properties of dust by comparing its emission to models. Taking advantage of the recent JWST data, in particular the spectroscopy of dust emission, we identify new constraints on dust and further previous works of dust modelling. Methods. To characterize interstellar dust across the Orion Bar, we follow its emission as traced by JWST NIRCam (at 3.35 and 4.8 μm) and MIRI (at 7.7, 11.3, 15.0, and 25.5 μm) broad band images, along with NIRSpec and MRS spectroscopic observations. First, we constrain the minimum size and hydrogen content of carbon nano-grains from a comparison between the observed dust emission spectra and the predictions of the Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS) coupled to the numerical code DustEM. Using this dust model, we then perform 3D radiative transfer simulations of dust emission with the SOC code (Scattering with OpenCL) and compare to data obtained along well chosen profiles across the Orion Bar. Results. The JWST data allows us, for the first time, to spatially resolve the steep variation of dust emission at the illuminated edge of the Orion Bar PDR. By considering a dust model with carbonaceous nano-grains and submicronic coated silicate grains, we derive unprecedented constraints on the properties of across the Orion Bar. To explain the observed emission profiles with our simulations, we find that the nano-grains must be strongly depleted with an abundance (relative to the gas) 15 times less than in the diffuse ISM. The NIRSpec and MRS spectroscopic observations reveal variations in the hydrogenation of the carbon nano-grains. The lowest hydrogenation levels are found in the vicinity of the illuminating stars suggesting photo-processing while more hydrogenated nano-grains are found in the cold and dense molecular region, potentially indicative of larger grains. [ABSTRACT FROM AUTHOR]

Context. The diffuse interstellar bands (DIBs) are a set of hundreds of unidentified absorption features that appear almost ubiquitously throughout the interstellar medium. Most DIBs appear at optical wavelengths, but some are in the near-infrared. Aims. We aim to characterise near-infrared DIBs at high spectral resolving power towards multiple targets. Methods. We observed 76 early-type stars at a resolving power of 50 000 (velocity resolution 6 km s1) and signal-to-noise ratios of several hundreds using the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES). These data allow us to investigate the DIBs around 1318.1, 1527.4, 1561.1, 1565.1, 1567.0, 1574.4, and 1624.2 nm. We detected a total of six DIB features and 17 likely stellar features through comparisons with a model spectrum computed with CMFGEN. Additionally, we measured equivalent widths of the DIBs at 1318.1 and 1527.4 nm using observations with X-shooter towards ten very highly reddened (3:2 < E(BV) < 6:5) Cepheid variable stars and towards four stars observed at low values of precipitable water vapour as well as by using other archive data. Results. We measured correlations (correlation coefficient r 0:73-0.96, depending on the subsample used) between DIB equivalent width and reddening for the DIBs at 1318.1, 1561.1, 1565.1, and 1567.0 nm. Comparing the near-infrared DIBs with 50 of the strongest optical DIBs, we find correlations r > 0:8 between the 1318, 1527, 1561, 1565, and 1567 nm and the optical DIBs 5705, 5780, 6203, 6283, and 6269 Å. The 5797 Å DIB is less well correlated with the near-infrared DIBs. The DIB at 9632.1 Å, which is likely C+ 60, is not well correlated with the 1318.1 nm DIB. Partial correlation coefficients using E(B-V) as the covariate were also determined. For stars earlier than B2, the 1318.1 nm DIB is affected by an emission line on its blue wing that is likely stellar in nature, although we cannot rule out an interstellar or circumstellar origin for this line caused by, for example, a DIB in emission. The 1318.1 nm DIB also has an extended red wing. The line is reasonably well fitted by two Gaussian components, although neither the component equivalent width (EW) ratios nor the separation between components are obviously correlated with such indicators as --5780/5797 and reddening. The EW at 1318 nm correlates with H I with EW(1318 nm)/E(B V) decreasing with f (H2). Five pairs of stars within one arcmin of each other show very similar 1318.1 nm DIB profiles. Possible variation in the 1318.1 nm feature is seen between HD145501 and HD145502 (separated by 41 arcsec, equivalent to 7200 au) and HD168607 and HD168625 (separated by 67 arcsec, equivalent to 0.52 pc on the plane of the sky). Seventeen sightlines have repeat CRIRES observations separated by six to 14 months, and two sightlines have repeat X-shooter observations separated by 9.9 yr. No time variability was detected in the 1318.1 nm DIB in the CRIRES data nor in the 5780.5 Å, 5797.1 Å, 1318.1 nm, and 1527.4 nm DIBs. Tentative time variation is observed in the C+ 60 DIBs at 9577 and 9632 Å towards HD183143, although it is very close to the noise level and requires confirmation. Conclusions. The Near Infrared (NIR) DIBs observed occur more in more UV-irradiated regions than the 5797 Å DIB allowing the study of heavily reddened sightlines. Future searches for time variability in DIBs will require either higher quality data, larger intervals between epochs, or both. [ABSTRACT FROM AUTHOR]

The Nearby Evolved Stars Survey (NESS) is a volume-complete sample of ∼850 Galactic evolved stars within 3 kpc at (sub-)mm wavelengths, observed in the CO J  = (2–1) and (3–2) rotational lines, and the sub-mm continuum, using the James Clark Maxwell Telescope and Atacama Pathfinder Experiment. NESS consists of five tiers, based on distances and dust-production rate (DPR). We define a new metric for estimating the distances to evolved stars and compare its results to Gaia EDR3. Replicating other studies, the most-evolved, highly enshrouded objects in the Galactic Plane dominate the dust returned by our sources, and we initially estimate a total DPR of 4.7 × 10−5 M⊙ yr−1 from our sample. Our sub-mm fluxes are systematically higher and spectral indices are typically shallower than dust models typically predict. The 450/850 |$\mu$| m spectral indices are consistent with the blackbody Rayleigh–Jeans regime, suggesting a large fraction of evolved stars have unexpectedly large envelopes of cold dust. [ABSTRACT FROM AUTHOR]

In the U.S., Deaf individuals who use a signed language as their preferred and dominant means of communication are considered a distinct linguistic and cultural group known as the Deaf community. Sign language interpreters, particularly non-native signers who are leaning ASL, are frequently encouraged to associate with the Deaf community as part of their language acquisition process. However, interpreters who are not deaf or native signers, especially students, often experience tension as they interact with the Deaf community. The literature is divided on whether hearing interpreters who learn ASL later in life, even those who are arguably bilingual and bicultural, are able to attain Deaf community membership. The guiding questions for this study are: According to their own perspectives, can hearing, ASL-English interpreters be members of the Deaf community? If they are members, what qualifies them as members, and if not, why not? Three interpreters were interviewed to elicit their views on hearing interpreters' fit within the Deaf community. Qualitative analysis in ELAN uncovered three primary themes; participants' definition of Deaf community and who can be a member, what participants' saw as requirements for interpreter membership, and caveats to such membership. While ASL fluency, attitude, and cultural competency were found to be important, a key finding is that participants agree interpreters' membership is dependent upon the Deaf community extending an invitation and is not something they can claim for themselves. [ABSTRACT FROM AUTHOR]

We report new spectroscopic observations of the magnetic Of?p star HD 148937 obtained since 2015 that differ qualitatively from its extensive historical record of weak, periodic spectral variations. This remarkable behaviour represents clear evidence for an unprecedented change in the character of variability of the star. In this paper, we describe the new spectral properties and compare them to the previous line profiles. Based on measurements of the radial velocities of the C  iii /N  iii emission lines near 4640 Å and the C  iv absorption lines near 5800 Å, we infer that HD 148937 is likely a high-mass, double-lined spectroscopic binary. Combining the spectroscopic orbit with an archival interferometric measurement of the apparent separation of the equal brightness components, we tentatively conclude that HD 148937 consists of two O-type stars with masses of approximately 34 and 49 M⊙, orbiting in an eccentric (e  = 0.75), long-period (P orb ∼ 26 yr) orbit. We discuss the potential relationship of the binary system to the peculiar properties of HD 148937, and propose future observations to refine the orbital and stellar properties. [ABSTRACT FROM AUTHOR]

Emission bands from polycyclic aromatic hydrocarbons (PAHs) dominate the mid-infrared spectra of a wide variety of astronomical sources, encompassing nearly all stages of stellar evolution. Despite their similarities, details in band positions and shapes have allowed a classification of PAH emission to be developed. It has been suggested that this classification is in turn associated with the degree of photoprocessing of PAHs. Over the past decade, a more complete picture of the PAH interstellar life-cycle has emerged, in which a wide range of PAH species are formed during the later stages of stellar evolution. After this they are photoprocessed, increasing the relative abundance of the more stable (typically larger and compact) PAHs. For this work we have tested the effect of the symmetry, size, and structure of PAHs on their fragmentation pattern and infrared spectra by combining experiments at the free electron laser for infrared experiments (FELIX) and quantum chemical computations. Applying this approach to the cations of four molecular species, perylene (C20H12), peropyrene (C26H14), ovalene (C32H14) and isoviolanthrene (C34H18), we find that a reduction of molecular symmetry causes the activation of vibrational modes in the 7–9 μm range. We show that the IR characteristics of less symmetric PAHs can help explain the broad band observed in the class D spectra, which are typically associated with a low degree of photoprocessing. Such large, nonsymmetrical irregular PAHs are currently largely missing from the NASA Ames PAH database. The band positions and shapes of the largest more symmetric PAH measured here, show the best resemblance with class A and B sources, representative of regions with high radiation fields and thus heavier photoprocessing. Furthermore, the dissociation patterns observed in the mass spectra hint to an enhanced stability of the carbon skeleton in more symmetric PAHs with respect to the irregular and less symmetric species, which tend to loose carbon containing units. Although not a direct proof, these findings are fully in line with the grandPAH hypothesis, which claims that symmetric large PAHs can survive as the radiation field increases, while their less symmetric counterparts are destroyed or converted to symmetric PAHs. [ABSTRACT FROM AUTHOR]

We present infrared (IR) and submillimetre observations of the Crab-like supernova remnant (SNR) G54.1+0.3 including 350 $$\mu$$ m (SHARC-II), 870 $$\mu$$ m (LABOCA), 70, 100, 160, 250, 350, and 500  $$\mu$$ m (Herschel), and 3–40  $$\mu$$ m (Spitzer). We detect dust features at 9, 11, and 21  $$\mu$$ m and a long-wavelength continuum dust component. The 21  $$\mu$$ m dust coincides with [Ar  ii ] ejecta emission, and the feature is remarkably similar to that in Cas A. The IRAC 8 $$\mu$$ m image including Ar ejecta is distributed in a shell-like morphology which is coincident with dust features, suggesting that dust has formed in the ejecta. We create a cold dust map that shows excess emission in the northwestern shell. We fit the spectral energy distribution of the SNR using the continuous distributions of ellipsoidal grain model of pre-solar grain SiO2 that reproduces the 21 and 9  $$\mu$$ m dust features and discuss grains of silicon carbide and polycyclic aromatic hydrocarbon that may be responsible for the 10–13  $$\mu$$ m dust features. To reproduce the long-wavelength continuum, we explore models consisting of different grains including Mg2SiO4, MgSiO3, Al2O3, FeS, carbon, and Fe3O4. We tested a model with a temperature-dependent silicate absorption coefficient. We detect cold dust (27–44 K) in the remnant, making this the fourth such SNR with freshly formed dust. The total dust mass in the SNR ranges from $$0.08\text{ to }0.9\, {\rm M}_{\odot }$$ depending on the grain composition, which is comparable to predicted masses from theoretical models. Our estimated dust masses are consistent with the idea that SNe are a significant source of dust in the early Universe. [ABSTRACT FROM AUTHOR]

It is well known that the dust properties of the di use interstellar medium exhibit variations towards di erent sight-lines on a large scale.We have investigated the variability of the dust characteristics on a small scale and from cloud-to-cloud.We use low-resolution spectro-polarimetric data obtained in the context of the Large Interstellar Polarisation Survey (LIPS) towards 59 sight-lines in the Southern Hemisphere and we fit these data using a dust model composed of silicate and carbon particles with sizes from the molecular to the sub-micrometre domain. Large (⩾6 nm) silicates of prolate shape account for the observed polarisation. For 32 sight-lines we complement our data set with UVES archive high-resolution spectra, which enable us to establish the presence of single-cloud or multiple-clouds towards individual sight-lines. We find that the majority of these 35 sight-lines intersect two or more clouds, while eight of them are dominated by a single absorbing cloud. We confirm several correlations between extinction and parameters of the Serkowski law with dust parameters, but we also find previously undetected correlations between these parameters that are valid only in single-cloud sight-lines. We find that interstellar polarisation from multiple-clouds is smaller than from single-cloud sightlines, showing that the presence of a second or more clouds depolarises the incoming radiation. We find large variations of the dust characteristics from cloud-to-cloud. However, when we average a suffciently large number of clouds in single-cloud or multiple-cloud sight-lines, we always retrieve similar mean dust parameters. The typical dust abundances of the single-cloud cases are [C]/[H] = 92 ppm and [Si]/[H] = 20 ppm. [ABSTRACT FROM AUTHOR]

We performed a detailed spectroscopic analysis of the fullerene C60-containing planetary nebula (PN) Lin49 in the Small Magellanic Cloud (SMC) using XSHOOTER at the European Southern Observatory Very Large Telescope and the Spitzer/Infrared Spectrograph instruments. We derived nebular abundances for nine elements. We used TLUSTY to derive photospheric parameters for the central star. Lin49 is C-rich and metal-deficient PN (Z ~ 0.0006). The nebular abundances are in good agreement with asymptotic giant branch nucleosynthesis models for stars with initial mass 1.25 M⊙ and metallicity Z = 0.001. Using the TLUSTY synthetic spectrum of the central star to define the heating and ionizing source, we constructed the photoionization model with CLOUDY that matches the observed spectral energy distribution (SED) and the line fluxes in the UV to far-IR wavelength ranges simultaneously. We could not fit the ~1-5 μm SED using a model with 0.005-0.1-μm-sized graphite grains and a constant hydrogen density shell owing to the prominent near-IR excess, while at other wavelengths the model fits the observed values reasonably well. We argue that the near-IR excess might indicate either (1) the presence of very small particles in the form of small carbon clusters, small graphite sheets, or fullerene precursors, or (2) the presence of a high-density structure surrounding the central star. We found that SMC C60 PNe show a near-IR excess component to lesser or greater degree. This suggests that these C60 PNe might maintain a structure nearby their central star. [ABSTRACT FROM AUTHOR]

Context. Photodissociation regions (PDRs) contain a large portion of all of the interstellar matter in galaxies. Classical examples include the boundaries between ionized regions and molecular clouds in regions of massive star-formation, marking the point where all of the photons that are energetic enough to ionize hydrogen have been absorbed. Aims. To determine the physical properties of the PDRs associated with the star-forming regions IRAS 23133+6050 and S 106 and present them in the context of other Galactic PDRs associated with massive star-forming regions. Methods. We employ Herschel PACS and SPIRE spectroscopic observations to construct a full 55-650 μm spectrum of each object from which we measure the PDR cooling lines, other fine- structure lines, CO lines, and the total far-infrared flux. These measurements (and combinations thereof) are then compared to standard PDR models. Subsequently, detailed numerical PDR models are compared to these predictions, yielding additional insight into the dominant thermal processes in the PDRs and their structures. Results. We find that the PDRs of each object are very similar and can be characterized by a two-phase PDR model with a very dense, highly UV irradiated phase (n ∼ 106 cm-3, G0 ∼ 105) interspersed within a lower density, weaker radiation field phase (n ∼ 104 cm-3, G0 ∼ 104). We employed two different numerical models to investigate the data. We first used RADEX models to fit the peak of the 12CO ladder, which in conjunction with the properties derived, yielded a temperature of around 300 K. Subsequent numerical modeling with a full PDR model revealed that the dense phase has a filling factor of around 0.6 in both objects. The shape of the 12CO ladder was consistent with these components, with heating dominated by grain photoelectric heating. An extra excitation component for the heightest-J lines (J > 20) is required for S 106. [ABSTRACT FROM AUTHOR]

We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in the Galactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (∼10−8–10−4 M⊙ yr−1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a function of age on the AGB. We observed our sample with Spitzer-Infrared Spectrograph, and studied the overall properties of the infrared spectra of these targets. The analysis is complicated by the presence of strong and variable background emission, and the extracted infrared AGB star spectra are affected by interstellar extinction. Several stars in our sample have no detectable dust emission, and we used these ‘naked stars’ to characterize the stellar and molecular contributions to the infrared spectra of our target stars. The resulting dust spectra of our targets do indeed show significant variety in their spectral appearance, pointing to differing dust compositions for the targets. We classify the spectra based on the shape of their 10-μm emission following the scheme by Sloan & Price. We find that the early silicate emission classes associated with oxide dust are generally under-represented in our sample due to extinction effects. We also find a weak 13-μm dust feature in two of our otherwise naked star spectra, suggesting that the carrier of this feature could potentially be the first condensate in the sequence of dust condensation. [ABSTRACT FROM PUBLISHER]

Context. The unknown identity of the diffuse interstellar band (DIB) carriers poses one of the longest standing unresolved problems in astrophysics. While the presence, properties, and behaviour of hundreds of optical DIBs between 4000 Å and 9000 Å have been well established, information on DIBs in both the ultra-violet and near-infrared (NIR) ranges is limited. Aims. In this paper, we present a spectral survey of the NIR range, from 0.9 μm to 2.5 μm. Our observations were designed to detect new DIBs, confirm previously proposed NIR DIBs, and characterise their behaviour with respect to known line-of-sight properties (including the optical DIBs present in our spectra). Methods. Using the X-Shooter instrument mounted on the ESO Very Large Telescope (VLT) we obtained medium-resolution spectra of eight known DIB targets and one telluric reference star, from 3000 Å to 25 000 Å in one shot. Results. In addition to the known 9577, 9632, 10 780, 11 797, and 13 175 Å NIR DIBs, we confirm 9 out of the 13 NIR DIBs that were presented by Geballe et al. (2011, Nature, 479, 200). Furthermore, we report 11 new NIR DIB candidates. The strengths of the strongest NIR DIBs show a general correlation with reddening, E(B- V), but with a large scatter. Several NIR DIBs are more strongly correlated with the 5780 Å DIB strength than with E(B- V); this is especially the case for the 15 268 Å DIB. The NIR DIBs are strong: the summed equivalent widths of the five strongest NIR DIBs represent a small percent of the total equivalent width of the entire average DIB spectrum (per unit reddening). The NIR DIBs towards the translucent cloud HD 147889 are all weak with respect to the general trend. No direct match was found between observed NIR DIBs and laboratory matrix-isolation spectroscopic data of polycyclic aromatic hydrocarbons (PAHs). Conclusions. The strong correlation between the 5780-15 268 DIB pair implies that (N f )5780/(N f )15268 = 14. However, the reduced strength of the 15 268 Å DIB in HD 147889 rules out a common carrier for these two DIBs. Since the ionisation fraction for small PAHs in this translucent cloud is known to be low compared to di use clouds, the weakness of the 15 268 Å DIB suggests that an ionised species could be the carrier of this NIR DIB. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of the mid-infrared spectrum of the peculiar evolved object HR 4049. The full Spitzer-IRS high-resolution spectrum shows a wealth of emission with prominent features from CO2 and H2O and possible contributions from HCN and OH. We model the molecular emission and find that it originates from a massive (M ≳ 8 × 10–3M☼), warm (Tex ≈ 500 K) and radially extended gas disk that is optically thick at infrared wavelengths. We also report less enrichment in 17O and 18O than previously found and a comparison of the Spitzer observations to earlier data obtained by the Short Wavelength Spectrometer on board the Infrared Space Observatory reveals that the CO2 flux has more than doubled in 10 yr time, indicating active and ongoing chemical evolution in the circumbinary disk. If the gas originates from interaction between the stellar wind and the dust, this suggests that the dust could be oxygen-rich in nature. The molecular gas plays a crucial role in the thermal properties of the circumbinary disk by allowing visible light to heat the dust and then trapping the infrared photons emitted by the dust. This results in higher temperatures and a more homogeneous temperature structure in the disk. [ABSTRACT FROM AUTHOR]

We present a road map of several research avenues leading to the identification of the diffuse interstellar band carriers. The proposed programs represent some consensus among the DIB community, and will certainly take many years to complete. However, the scientific payoff will be huge, and will ultimately lead to the solution of the DIB problem. [ABSTRACT FROM PUBLISHER]

Fullerenes and their derivatives are amongst the most stable carbonaceous species known and have therefore been proposed as ideal candidates to carry some of the diffuse interstellar bands (DIBs). Evidence for these species in space first came from a few DIBs that have been tentatively identified with electronic transitions of C60+; in recent years, infrared observations have furthermore revealed fullerenes in a variety of circumstellar and interstellar environments. With the presence of the fullerene family in space established, we review what is known about cosmic fullerenes and their derivatives and what role they could play as potential DIB carriers. [ABSTRACT FROM PUBLISHER]

Establishing the stability of cosmic fullerenes and fullerenic aggregates is extremely relevant for a variety of reasons. For instance, the emission features of C60 and C70 fall in the same spectral region as the Un-identified InfraRed (UIR) bands, which they could contribute to. To be able to contribute to the UIR emission, however, fullerenes must be able to survive long enough against the destruction mechanisms operating in the interstellar medium. In this study we focus on the effects of collisional processing, i.e., the bombardment by energetic ions and electrons. A recent experimental/theoretical study has shown that ion collisions with C60 clusters result in the dissociation of the cluster with the simultaneous formation of covalent fullerene dimers, which could play a role as DIBs carriers. We present here our first results about the collisional processing of C60 molecules and clusters by H, He and C ions in interstellar shocks. We have adapted the models that have previously been developed to successfully treat the collisional processing of PAHs in space. The nature of the interaction and the similarities between PAHs and fullerenes make this approach appropriate. In addition, our study shows that the formation of covalent dimers following ion collisions with C60 clusters is compatible with the astrophysical conditions under consideration. [ABSTRACT FROM PUBLISHER]

We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3040-3700 Å). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early type stars – typical diffuse interstellar band (DIB) targets. We stacked the individual observations to obtain a spectrum with a signal-to-noise ratio exceeding 1500. Careful inspection of this spectrum reveals tens of absorption features of interstellar nature, most of which can be identified with various atomic and molecular features. We furthermore detect four weak unidentified features, but we cannot establish their interstellar nature. Our sensitivity is limited by telluric and instrumental residuals; this precludes us from detecting broader features (e.g. DIBs). For each detected feature, we measured fundamental parameters (radial velocities, line widths, and equivalent widths). We also compare our co-added spectrum to cold gas-phase laboratory measurements of small, neutral polycyclic aromatic hydrocarbon (PAH) molecules. [ABSTRACT FROM PUBLISHER]

We report on the discovery of an infrared emission band in the Spitzer spectrum of the S-type AGB star NP Aurigae that is caused by TiO molecules in the circumstellar environment. We modeled the observed emission to derive the temperature of the TiO molecules (≈600K), an upper limit on the column density (≈1017.25 cm-2) and a lower limit on the spatial extent of the layer that contains these molecules. (≈4.6 R"). This is the first time that this TiO emission band is observed. A search for similar emission features in the sample of S-type stars yielded two additional candidates. However, owing to the additional dust emission, the identification is less stringent. By comparing the stellar characteristics of NP Aur to those of the other stars in our sample, we find that all stars with TiO emission show large-amplitude pulsations, s-process enrichment, and a low C/O ratio. These characteristics might be necessary requirements for a star to show TiO in emission, but they are not sufficient. [ABSTRACT FROM AUTHOR]

Carbon-rich evolved stars from the asymptotic giant branch to the planetary nebula phase are characterized by a rich and complex carbon chemistry in their circumstellar envelopes. A peculiar object is the preplanetary nebula SMP LMC 11, whose Spitzer Infrared Spectrograph spectrum shows remarkable and diverse molecular absorption bands. To study how the molecular composition in this object compares to our current understanding of circumstellar carbon chemistry, we modeled this molecular absorption. We find high abundances for a number of molecules, perhaps most notably benzene. We also confirm the presence of propyne (CH3C2H) in this spectrum. Of all the cyanopolyynes, only HC3N is evident; we can detect at best a marginal presence of HCN. From comparisons to various chemical models, we can conclude that SMP LMC 11 must have an unusual circumstellar environment (a torus rather than an outflow). [ABSTRACT FROM AUTHOR]

We use the NASA Ames Polycyclic Aromatic Hydrocarbon (PAH) infrared spectroscopic database to model infared emission of PAHs following absorption of a UV photon. We calculate emission spectra resulting from the full cooling cascade for each species in the database. Using a least squares approach, we can find out what PAH mixtures best reproduce a few typical astronomical observations representing the different classes of UIR spectra. We find that we can reproduce the observed UIR spectra in the wavelength range 6-14 µm, offering support for the hypothesis that the UIR bands are indeed due to vibrational modes of PAHs and related molecular species. Spectral decompositions of our best fit models confirm and reinforce several earlier results: (i) the 6.2 µm band requires a significant contribution of nitrogen-substituted PAHs (PANHs); (ii) the reported components and their variations in the 7.7 µm band are indicative of changes in the size distribution of the contributing molecules; (iii) there is a significant contribution of anions to the 7.7 µm band; (iv) the 11.2 µm band is due to large, neutral and pure PAHs; (v) the 11.0 µm band is due to large PAH cations. [ABSTRACT FROM AUTHOR]

Polycyclic Aromatic Hydrocarbons (PAHs) are widespread across the Universe and influence many stages of the Galactic lifecycle. The presence of PAHs has been well established and the rich mid-IR PAH spectrum is now commonly used as a probe into (inter)stellar environments. The NASA Ames PAH IR Spectroscopic Database has been key to test and refine the "PAH hypothesis". This database is a large coherent set (>600 spectra) of laboratory measured and DFT computed infrared spectra of PAHs from C10H8 to C130H28 and has been made available on the web at (http://www.astrochem.org/pahdb). With a new spectral window opening up; the far-IR, the study of PAH far-IR spectra and the quest for identifying a unique member of the interstellar PAH family has begun. To guide this research, the far-IR (>20 pm) spectra of different sets of PAHs are investigated using the NASA Ames PAH IR Spectroscopic Database. These sets explore the influence of size, shape, charge and composition on the far-IR PAH spectrum. The far-IR is also the domain of the so-called "drumhead" modes and other molecular vibrations involving low order bending vibrations of the carbon skeleton as a whole. As with drums, these are molecule and shape specific and promise to be a key diagnostic for specific PAHs. Here, the sensitivity of these "drumhead" modes to size and shape is assessed by comparing the frequencies of the lowest drumhead modes of a family of circular shaped (the coronene "family") and rhombus shaped (the pyrene "family") PAH molecules. From this study, some consequences for an observing strategy are drawn. [ABSTRACT FROM AUTHOR]

Studies the non-linear pharmacokinetics of methylenedioxymethamphetamine (MDMA or ecstacy) in humans in Great Britain. Pharmacological effects of the drug; Pharmacokinetic parameters for MDMA and methylenedioxyphetamine (MDA); Assessment of MDMA and MDA.

Long-term opioid consumption can induce hypoadrenalism through impairment of the hypothalamic-pituitary-adrenal axis. Results of the present study showed that, in heroin addicts, saliva cortisol concentrations varied according to the amount of recently consumed heroin and the time elapsed since the last self-administration. Hypercortisolism was observed either after abrupt withdrawal of heroin or the last dose of methadone. Post-detoxification hypercortisolism was still present on day 16 after the last opioid consumption, whereas it was not observed in abstinent addicts for a mean period of 4 months. During detoxification treatment, mean AUC[sub 8-24] cortisol in saliva of clonidine or guanfacine-treated patients was significantly higher than that in methadone-treated patients. It may be hypothesized that elevated cortisol levels may account for untoward effects of adrenergic agonist therapy which, in turn, may represent an added risk factor for relapse during detoxification. Further studies are necessary to correlate the severity of withdrawal symptoms to cortisol levels in opioid addicts detoxified with α[sub 2]-adrenergic agonist substitution. [ABSTRACT FROM AUTHOR]

In the early 80's opioid addiction was a low prevalence problem in Spain, grew enormously during that decade and became the most important risk factor for AIDS in recent years. The limitations of assessing the prevalence of illegal drug use by means of standard epidemiological methods lead, worldwide, to the use of indirect indicators. A Register of Toxicological Emergencies. developed for research purposes and containing data from 1979 to 1989 at the Hospital del Mar (Barcelona) is described. Results for opioid-related emergencies are presented, showing an epidemic increase in the number of such emergencies after 1981. The total number of opioid-related emergencies was 18042 with a mean of 2.23 opioid-related emergency admissions per client throughout the whole period, implying that some 8000 persons were seen. In episodes Prom non-arrestees, mean age increased slightly over time, the male/female ratio being 2.5; withdrawal was the more frequent reason for attendance (53%), overdoses accounting for 9% of admissions, and other medical conditions for 33%. Non-arrested women were more likely to attend for other medical conditions and overdoses than men. The importance of this kind of register as well as its limitations for assessing the trend of opioid use prevalence is discussed. [ABSTRACT FROM AUTHOR]

Presents research which reported infrared observations of the Red Rectangle that revealed the presence of oxygen-rich material. What the Red Rectangle is; The central star of this nebula; What the oxygen-rich material is and where it is located; Properties of the material; Possibility that grain processing or planet formation are occurring around the evolved star.

We have observed ten carbon stars with different mass-loss rates using the Short Wavelength Spectrometer (SWS) on board ISO. We found that not only the spectral energy distribution and the dust features, but that also that the strength and/or shape of molecular absorption features in the infrared spectrum varies with the near-infrared color temperature, i.e. with the thickness of the circumstellar envelope. [ABSTRACT FROM AUTHOR]

We present ISO observations of bright, high-mass southern starforming regions with the Short Wavelength Spectrometer (SWS) and Long Wavelength Spectrometer (LWS). The selected targets show a range of pre-main sequence evolutionary phases. Whereas some objects still show interstellar ice features, the most evolved objects are coincident with ultra-compact HII regions and show strong emission lines from atomic species and polycyclic aromatic hydrocarbons (PAHs). We discuss the ISO spectra between 2.5 - 200 µm of selected southern star-forming regions in the context of their evolution. [ABSTRACT FROM AUTHOR]

The pharmacokinetics and tolerance of repeated oral doses of furafylline were investigated in normal volunteers. In accord with predictions from single dose studies, steady state was achieved on the first day following the administration of 90 mg and maintained by subsequent daily doses of 30 mg. When corrected for body weight there were no significant differences in minimum and maximum plateau levels of furafylline between males (1.2-2.0 micrograms ml-1; mean body weight 67.2 kg) and females (1.6-2.6 micrograms ml-1; mean body weight 54.9 kg). The half-life of elimination was less when the plasma concentration was lower than 600 ng ml-1 than during the stationary phase of treatment. Despite constant plasma levels the repeated administration of furafylline appeared to be associated with the onset of adverse xanthine-like side effects, a finding which was subsequently traced to the presence of, and possible synergism with, accumulating serum levels of caffeine in those volunteers drinking caffeine containing beverages. Subsequent studies showed that a single dose (90 mg) of furafylline results in a rapid accumulation of caffeine given orally (100 mg twice daily) and that this is accompanied by an elimination half-life of some 50 h and an abrupt decrease in metabolite levels. The furafylline-induced accumulation of caffeine was not influenced by the smoking habits of the subjects, implying that the metabolite pathway blocked by furafylline is the demethylation of caffeine in position 3, an implication confirmed by the reduced formation of paraxanthine. This demonstration of an unacceptable level of adverse side effects resulting from a potent inhibiting effect of furafylline on the metabolism of a normal dietary constituent has obvious implications in the interpretation of drug-induced toxicity. [ABSTRACT FROM AUTHOR]

Naltrexone and placebo as adjuvant treatment of opioid dependence were compared in a double-blind, controlled clinical trial in 50 heroin addicts. The overall efficacy was assessed by the degree of treatment acceptance, percentage of relapse in heroin consumption, presence of side effects, and overall retention on naltrexone. A total of SO patients of both sexes, aged from 18 to 30years, who fulfilled DSM-III-R criteria for opioid dependence were included in the study. All patients completed detoxification with clonidine on an inpatient basis for 2 weeks and subsequently, on an out-patient basis, received oral naltrexone 050 mg per week) for a month. At the beginning of the second month patients were randomly allocated to treatment with nalirexone (28 patients) or placebo (22 patients) until a 6-month treatment period in a double-blind fashion had been completed. During the study period (1 year) all patients followed the same therapeutic schedule. Patients in both groups were comparable in terms of socio-demographic data and toxicological history. The efficacy of naltrexone was not superior to that of placebo as there were no significant differences in acceptance of treatment, retention rates, opioid and other drug consumption, drug compliance or side effects. [ABSTRACT FROM AUTHOR]

We present a preliminary analysis of a set of optical (3800-8800 Å) high resolution (R = 80,000) spectra for 69 diffuse interstellar band targets. We carried out a sensitive search for interstellar features in the wavelength range 8470-8740 Å that will be covered by the upcoming GAIA mission. We also investigate how the λ8620Å DIB strength varies as a function of other interstellar parameters (other DIBs, E(B-V) and atomic and molecular column densities). [ABSTRACT FROM PUBLISHER]

We present the first results of an exploratory VLT/X-Shooter survey of near-infrared diffuse interstellar bands (DIBs) in diffuse to translucent interstellar clouds. These observations confirm the presence of recently discoved NIR DIBs and provide more accurate rest wavelengths and line widths. Example spectra are shown for the reddened, AV ~ 10 mag, line-of-sight towards the distant binary system 4U 1907+09. [ABSTRACT FROM PUBLISHER]

Supernovae (SNe) produce, fragment and destroy dust, molecules and nucleosynthetic elements, and reshape and modify the ISM. I will review recent infrared observations of supernova remnants (SNRs) and SNe which show that SNe are important sites of dust and molecule formation and are major dust creators in the Universe. Detection of carbon monoxide (CO) fundamental band from the young SNR Cas A indicates that astrochemical processes in SNRs interacting with molecular clouds provide astrophysical laboratories to study evolution of the ISM returning material from dense clouds into the more diffuse medium and galactic halo. Two dozen SNRs are known to be interacting with molecular clouds using H2 and millimeter observations. Recent Spitzer, Herschel and SOFIA observations along with ground-based observations have greatly advanced our understanding shock processing and astrochemistry of dust, H2, high J CO, and other neutral and ionized molecules and polycyclic aromatic hydrocarbon (PAH). Ionized molecules and warm layer of molecules that are excited by UV radiation, X-rays, or cosmic rays will be described. Finally I will discuss how astrochemical processes of dust and molecules in SNRs impact the large scale structures in the ISM. [ABSTRACT FROM PUBLISHER]

Supernovae (SNe) produce, fragment and destroy dust, molecules and nucleosynthetic elements, and reshape and modify the ISM. I will review recent infrared observations of supernova remnants (SNRs) and SNe which show that SNe are important sites of dust and molecule formation and are major dust creators in the Universe. Detection of carbon monoxide (CO) fundamental band from the young SNR Cas A indicates that astrochemical processes in SNRs interacting with molecular clouds provide astrophysical laboratories to study evolution of the ISM returning material from dense clouds into the more diffuse medium and galactic halo. Two dozen SNRs are known to be interacting with molecular clouds using H2 and millimeter observations. Recent Spitzer, Herschel and SOFIA observations along with ground-based observations have greatly advanced our understanding shock processing and astrochemistry of dust, H2, high J CO, and other neutral and ionized molecules and polycyclic aromatic hydrocarbon (PAH). Ionized molecules and warm layer of molecules that are excited by UV radiation, X-rays, or cosmic rays will be described. Finally I will discuss how astrochemical processes of dust and molecules in SNRs impact the large scale structures in the ISM. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of dust production on the molecular absorption, we model the dust continuum and the 7.5 and 13.7 μ m acetylene absorption features in the Spitzer IRS spectra of 148 carbon stars in the Large Magellanic Cloud (LMC). Our preliminary investigation does not find a strong correlation between the dust-production rate and the column density of acetylene for the LMC sample. However, we will construct more models at high optical depths and probe a larger range of dust properties for more robust results. [ABSTRACT FROM AUTHOR]

We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2 μm, 5.5 μm, and 10.6 μm; at longer wavelengths, there is a forest of emission features in the 16-30 μm range that appears as a structured continuum, but with a clear peak centered around 19 μm. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC 7023. We find a weak emission feature at 10.68 μm in all positions except that closest to the central star. We also find evidence for a weak 19 μm feature at all positions that is not likely due to C60. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes. [ABSTRACT FROM AUTHOR]

HR 4049 is a peculiar evolved binary surrounded by a circumbinary disk. Mid-infrared observations show that the disk is rich in molecular gas and radially extended. To study the properties of this disk, we re-analyzed a set of near-infrared observations at high spectral resolution obtained with Gemini-Phoenix. These data cover absorption lines originating from the first overtone of CO and from H2O in the 2.3 μm region as well as more complex emission-absorption profiles from H2O and the fundamental mode of CO near 4.6 μm. By using an excitation diagram and from modeling the spectrum, we find that most of the CO overtone and H2O absorption originates from hot gas (Tex ≈ 1000 K) with high column densities, consistent with the mid-infrared data. The strong emission in the wavelength range of the CO fundamental furthermore suggests that there is a significant quantity of gas in the inner cavity of the disk. In addition, there is a much colder component in the line of sight to the disk. A detailed analysis of the overtone line profiles reveals variations in the line widths that are consistent with a radially extended disk in Keplerian rotation with hotter gas closer to the central star. We estimate the mass of the primary to be ∼0.34 M☼ and discuss the implications for its evolutionary status. [ABSTRACT FROM AUTHOR]

We present the spectra of 5 OH/IR stars observed with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by dust features, both in the amorphous and crystalline state and illustrate the influence of the mass loss rate on the observed spectral features. [ABSTRACT FROM AUTHOR]

Infrared spectra of carbon-rich objects that have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 μm emission feature. To test for the presence of fullerenes, we used the position and width of the feature at 18.7-18.9 μm and examined other features at 17.4 and 6-9 μm. This method adds three new fullerene sources to the known sample, but it also calls into question three previous identifications. We confirm that the strong 11 μm features seen in some sources arise primarily from SiC, which may exist as a coating around carbonaceous cores and result from photo-processing. Spectra showing the 21 μm feature usually show the newly defined Class D PAH profile at 7-9 μm. These spectra exhibit unusual PAH profiles at 11-14 μm, with weak contributions at 12.7 μm, which we define as Class D1, or show features shifted to ∼11.4, 12.4, and 13.2 μm, which we define as Class D2. Alkyne hydrocarbons match the 15.8 μm feature associated with 21 μm emission. Sources showing fullerene emission but no PAHs have blue colors in the optical, suggesting a clear line of sight to the central source. Spectra with 21 μm features and Class D2 PAH emission also show photometric evidence for a relatively clear line of sight to the central source. The multiple associations of the 21 μm feature with aliphatic hydrocarbons suggest that the carrier is related to this material in some way. [ABSTRACT FROM AUTHOR]

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds: Tc1, SMP SMC 16, and SMP LMC 56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C60 and little or no emission is present from polycyclic aromatic hydrocarbons. The strengths of the fullerene bands in the three planetary nebulae are very similar, while the ratios of the [Ne III]15.5 μm/[Ne II]12.8 μm fine structure lines, an indicator of the strength of the radiation field, are markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9 μm region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled hydrogenated amorphous carbon that present emission in this region. [ABSTRACT FROM AUTHOR]