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The corroded surfaces of historical glass samples were studied by micro‐Raman spectroscopy. The spectra acquired from lateral and stratified mapping were analyzed by principal component analysis providing the number of linearly independent spectral components and by multivariate curve analysis resulting in spectrum of native glass and spectra of different corrosion products (loadings) and their relative abundances (scores) in each measured spot. The obtained results were qualified by comparison of results obtained by stratified mapping with the results of lateral mapping. On the basis of dominant scores, the lateral distribution of various corrosion products was identified. The quality of corrosion products was only roughly identified by the spectral database (S.T. Japan spectral database). [ABSTRACT FROM AUTHOR]

Three solid state formation routes have been proposed in the past to explain the observed abundance of water in space: the hydrogenation reaction channels of atomic oxygen (O + H), molecular oxygen (O2 + H), and ozone (O3 + H). New data are presented here for the third scheme with a focus on the reactions O3 + H, OH + H and OH + H2, which were difficult to quantify in previous studies. A comprehensive set of H/D-atom addition experiments is presented for astronomically relevant temperatures. Starting from the hydrogenation/deuteration of solid O3 ice, we find experimental evidence for H2O/D2O (and H2O2/D2O2) ice formation using reflection absorption infrared spectroscopy. The temperature and H/D-atom flux dependence are studied and this provides information on the mobility of ozone within the ice and possible isotope effects in the reaction scheme. The experiments show that the O3 + H channel takes place through stages that interact with the O and O2 hydrogenation reaction schemes. It is also found that the reaction OH + H2 (OH + H), as an intermediate step, plays a prominent (less efficient) role. The main conclusion is that solid O3 hydrogenation offers a potential reaction channel for the formation of water in space. Moreover, the nondetection of solid ozone in dense molecular clouds is consistent with the astrophysical picture in which O3 + H is an efficient process under interstellar conditions. [ABSTRACT FROM AUTHOR]

Highlights • We confirm 21 olivine-dominated spectral A-type asteroids in the main belt. • We determine 0.16% of the main belt is A-type. • The distribution of A-types as a function of semi-major axis is relatively flat. • We reaffirm there is no significant undiscovered A-type material down to −2 km. • We find no statistically significant relationship with A-types and asteroid families. Abstract Differentiated asteroids are rare in the main asteroid belt despite evidence for ∼ 100 distinct differentiated bodies in the meteorite record. We have sought to understand why so few main-belt asteroids differentiated and where those differentiated bodies or fragments reside. Using the Sloan Digital Sky Survey (SDSS) to search for a needle in a haystack we identify spectral A-type asteroid candidates, olivine-dominated asteroids that may represent mantle material of differentiated bodies. We have performed a near-infrared spectral survey with SpeX on the NASA IRTF and FIRE on the Magellan Telescope. We report results from having doubled the number of known A-type asteroids. We deduce a new estimate for the overall abundance and distribution of this class of olivine-dominated asteroids. We find A-type asteroids account for less than 0.16% of all main-belt objects larger than 2 km and estimate there are a total of ∼ 600 A-type asteroids above that size. They are found rather evenly distributed throughout the main belt, are even detected at the distance of the Cybele region, and have no statistically significant concentration in any asteroid family. We conclude the most likely implication is the few fragments of olivine-dominated material in the main belt did not form locally, but instead were implanted as collisional fragments of bodies that formed elsewhere. [ABSTRACT FROM AUTHOR]

Transmission spectroscopy of exoplanets has the potential to provide precise measurements of atmospheric chemical abundances, in particular of hot Jupiters whose large sizes and high temperatures make them conducive to such observations. To date, several transmission spectra of hot Jupiters have revealed low amplitude features of water vapour compared to expectations from cloud-free atmospheres of solar metallicity. The low spectral amplitudes in such atmospheres could either be due to the presence of aerosols that obscure part of the atmosphere or due to inherently low abundances of H2O in the atmospheres. A recent survey of transmission spectra of ten hot Jupiters used empirical metrics to suggest atmospheres with a range of cloud/haze properties but with no evidence for H2O depletion. Here, we conduct a detailed and homogeneous atmospheric retrieval analysis of the entire sample and report the H2O abundances, cloud properties, terminator temperature profiles, and detection significances of the chemical species. This study finds that the majority of hot Jupiters have atmospheres consistent with subsolar H2O abundances at their day–night terminators. The best constrained abundances range from log(H2O) of |$-5.04^{+0.46}_{-0.30}$| to |$-3.16^{+0.66}_{-0.69}$|⁠, which compared to expectations from solar-abundance equilibrium chemistry correspond to |$0.018^{+0.035}_{-0.009}\times$| solar to |$1.40^{+4.97}_{-1.11}\times$| solar. Besides H2O we report statistical constraints on other chemical species and cloud/haze properties, including cloud/haze coverage fractions which range from |$0.18^{+0.26}_{-0.12}$| to |$0.76^{+0.13}_{-0.15}$|⁠. The retrieved H2O abundances suggest subsolar oxygen and/or supersolar C/O ratios, and can provide important constraints on the formation and migration pathways of hot giant exoplanets. [ABSTRACT FROM AUTHOR]

We compile available constraints on the carbon monoxide (CO) 1-0 luminosity functions and abundances at redshifts 0-3. This is used to develop a data driven halo model for the evolution of the CO galaxy abundances and clustering across intermediate redshifts. It is found that the recent constraints from the CO Power Spectrum Survey (z ~ 3; Keating et al. 2016), when combined with existing observations of local galaxies (z ~ 0; Keres, Yun & Young 2003), lead to predictions that are consistent with the results of smaller surveys at intermediate redshifts (z ~ 1-2). We provide convenient fitting forms for the evolution of the CO luminosity-halo mass relation, and estimates of the mean and uncertainties in the CO power spectrum in the context of future intensity mapping experiments. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify highvelocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as CIV λλ1548,1551, typically provide only a lower limit because of saturation effects. Low abundance lines, such as P V λλ1118,1128, indicate large column densities, implying that outflows more powerful than measurements of C IV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 ‘definite’ and 86 ‘probable’ detections of P V broad absorption, yielding a firm lower limit of 3.0–6.2 per cent for the incidence of such absorption among BAL quasars. The P V-detected quasars tend to have stronger C IV and Si IV absorption, as well as a higher incidence of LoBAL absorption, than the overall BAL quasar population. Many of the P V-detected quasars have C IV troughs that do not reach zero intensity (at velocities where P V is detected), confirming that the outflow gas only partially covers the UV continuum source. P V appears significantly in a composite spectrum of non-P V-detected BAL quasars, indicating that P V absorption (and large column densities) is much more common than indicated by our search results. Our sample of P V detections significantly increases the number of known P V detections, providing opportunities for follow-up studies to better understand BAL outflow energetics. [ABSTRACT FROM AUTHOR]

Extremely metal-poor (EMP) stars are old objects formed in the first Gyr of the Universe. They are rare and, to select them the most successful strategy has been to build on large and low-resolution spectroscopic surveys. The combination of narrow- and broad-band photometry provides a powerful and cheaper alternative to select metal-poor stars. The ongoing Pristine Survey is adopting this strategy, conducting photometry with the Canada France Hawaii Telescope MegaCam wide-field imager and a narrow-band filter centered at 395.2 nm on the Ca II-H and -K lines. In this paper, we present the results of the spectroscopic follow-up conducted on a sample of 26 stars at the bright end of the magnitude range of the Survey ( g⩽15), using FEROS at the MPG/ESO 2.2-m telescope (manufactured by Zeiss, Oberkochen, Germany). From our chemical investigation on the sample, we conclude that this magnitude range is too bright to use the Sloan Digital Sky Survey (SDSS) g r i bands, which are typically saturated. Instead, the Pristine photometry can be usefully combined with the AAVSO Photometric All Sky Survey (APASS) g r iphotometry to provide reliable metallicity estimates. [ABSTRACT FROM AUTHOR]

With the upcoming release of the Gaia catalog and the many multiplexed spectroscopic surveys on the horizon, we are rapidly moving into a new data-driven era in the study of the Milky Way's stellar halo. When combined, these data sets will give us a many-dimensional view of stars in accreted structures in the halo that includes both dynamical information about their orbits and chemical information about their formation histories. Using simulated data from the state-of-the-art Latte simulations of Milky-Way-like galaxies, which include hydrodynamics, feedback, and chemical evolution in a cosmological setting, we demonstrate that while dynamical information alone can be used to constrain models of the Galactic mass distribution in the halo, including the extra dimensions provided by chemical abundances can improve these constraints as well as assist in untangling different accreted components. [ABSTRACT FROM AUTHOR]

Context: Integrated-light spectroscopy at high spectral resolution is rapidly maturing as a powerful way to measure detailed chemical abundances for extragalactic globular clusters (GCs). Aims: We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Methods: Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved Hubble Space Telescope colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. Results: The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than ~0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the ff-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr=Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg=Fe] ratios also agree well with literature data. Our [Na=Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba=Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Conclusions: Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects, might further reduce some of the remaining offsets. [ABSTRACT FROM AUTHOR]

Abstract We obtained the surface abundances of more than 20 elements from H- and K-band observations of three Red Horizontal Branch (RHB) stars. High-resolution (R ≃ 45,000) infrared spectra were obtained using IGRINS (the Immersion Grating Infrared Spectrograph) on the 2.7 m Smith telescope at McDonald Observatory. IGRINS has the capacity of making simultaneous observations with a wavelength coverage of essentially the entire H and K-bands (1.5–2.4 μm). High S/N (>200) IGRINS data serve as a laboratory of molecular bands. A large number of OH, CO and CN molecular bands provided us invaluable information on the abundances of C, N and O, which can be altered as stars evolve from birth to death. OH bands confirmed and greatly strengthened the oxygen abundances previously measured from visible [O I] lines. Carbon and nitrogen abundances were determined from CO and CN molecular bands, respectively. IGRINS also made it possible to achieve more robust abundances of light elements such as Na, Mg, Al, and Si than obtained from their visible counterparts, and allowed S, P and K abundance determination mostly for the first time. Most importantly, we were able to detect 12C/13C isotopic ratios from the CO (2–0) and CO (3–1) band-heads present in the K-band, which give us important clues about the evolutionary status of the stars and mixing processes that take place in the interiors of these RHB He core-burning stars. [ABSTRACT FROM AUTHOR]

Sulfur and zinc are chemically volatile elements, which play significant roles as depletion-free tracers in studying galactic chemical evolution. However, regarding red giants having evolved off the main sequence, reliable abundance determinations of S and Zn seem to be difficult, despite the several studies that have been reported so far. Given this situation, we tried to establish the abundances of these elements for an extensive sample of 239 field GK giants (-0.8 ≲ [Fe/H] ≲ +0.2), by applying the spectrum-fitting technique to S | 8694-5, S | 6757, and Zn | 6362 lines and by taking into account the non-LTE effect. Besides, similar abundance analysis was done for 160 FGK dwarfs to be used for comparison. The non-LTE corrections for the S and Zn abundances derived from these lines turned out to be ≲ 0.1(-0.2) dex for most cases and not very significant. It revealed that the S | 6757 feature is more reliable as an abundance indicator than S | 8694-5 for the case of red giants, because the latter suffers blending of unidentified lines. The finally resulting [S/Fe]-[Fe/H] and [Zn/Fe]-[Fe/H] relations for GK giants were confirmed to be in good agreement with those for FGK dwarfs, indicating that S and Zn abundances of red giants are reliably determinable from the S | 6757 and Zn | 6362 lines. Accordingly, not only main-sequence stars but also evolved red giant stars are usable for tracing the chemical evolution history of S and Zn in the regime of disk metallicity by using these lines. [ABSTRACT FROM AUTHOR]

Hydrodynamical, i.e. multi-dimensional and time-dependent, model atmospheres of late-type stars have reached a high level of realism. They are commonly applied in high-fidelity work on stellar abundances but also allow the study of processes that are not modelled in standard, one-dimensional hydrostatic model atmospheres. Here, we discuss two observational aspects that emerge from such processes, the photometric granulation background and the spectroscopic microturbulence. We use CO5BOLD hydrodynamical model atmospheres to characterize the total granular brightness fluctuations and characteristic time scale for FGK stars. Emphasis is put on the diagnostic potential of the granulation background for constraining the fundamental atmospheric parameters. We find a clear metallicity dependence of the granulation background. The comparison between the model predictions and available observational constraints at solar metallicity shows significant differences, that need further clarification. Concerning microturbulence, we report on the derivation of a theoretical calibration based on CO5BOLD models, which shows good correspondence with the measurements for stars in the Hyades. We emphasize the importance of a consistent procedure when determining the microturbulence, and point to limitations of the commonly applied description of microturbulence in hydrostatic model atmospheres. [ABSTRACT FROM AUTHOR]

Data drawn from the published literature are used to define the relations between the spectroscopic λ4215 CN-band strength of red giants in the globular cluster Messier 71 and both the sodium and oxygen abundances. The cluster giants with CN measurements included in this study have absolute magnitudes in the range -2 < MV < +2. The data are consistent with a moderate degree of anticorrelation between the CN-band strength and the [O/Fe] abundance, as well as a moderate correlation between CN-band strength and [Na/Fe], although there is scatter of up to 0.3-0.4 dex in both O and Na abundance among giants with CN bands of similar strength. The mean difference in [O/Fe] between CN-strong and CN-weak giants is 0.13 dex, the former group of stars having the lower average oxygen abundance. By contrast, the mean difference in [Na/Fe] between CN-strong and CN-weak giants is 0.17 dex, with the CN-strong group having the higher average sodium abundance. There is a similar range in λ4215 CN-band strengths among the red giants in Messier 71 and 47 Tucanae. Furthermore, the red giant branch stars in the two clusters follow very similar relations between CN-band strength and [Na/Fe] abundance. These two similarities are intriguing given that the two clusters differ by a factor of 30 or more in luminous mass, with 47 Tuc having a much higher degree of central mass concentration than M71. A difference can be discerned between the O- CN relations in the two clusters, such that for a given CN-band strength the CN-strong giants in 47 Tuc attain lower values of [O/Fe], a result that is consistent with previously noted differences in the O-Na relations of the two objects. A scenario is discussed in which both 47 Tuc and M71 were formed as the mergers of pre-existing CN-weak and CN-strong subclusters, the later having been formed following chemical evolution and self-enrichment of a large cloud complex that had earlier formed the CN-weak subcluster. Different dynamical merger routes may have lead in one instance to the high-mass 47 Tuc cluster, whereas M71 may have resulted from a merger that was accompanied by a large amount of star loss and stellar evaporation. [ABSTRACT FROM AUTHOR]

We report on high-resolution and spatially-resolved spectra of Io in the 4.0 μm region, recorded with the VLT/CRIRES instrument in 2008 and 2010, which provide the first detection of the ν 1 + ν 3 band of SO 2 in Io’s atmosphere. Data are analyzed to constrain the latitudinal, longitudinal, and diurnal distribution of Io’s SO 2 atmosphere as well as its characteristic temperature. Equatorial SO 2 column densities clearly show longitudinal asymmetry, but with a maximum of ∼1.5 × 10 17 cm −2 at central meridian longitude L = 200–220 and a minimum of ∼3 × 10 16 cm −2 at L = 285–300, the longitudinal pattern somewhat differs from earlier inferences from Ly α and thermal IR measurements. Within the accuracy of the measurements, no evolution of the atmospheric density from mid-2008 to mid-2010 can be distinguished. The decrease of the SO 2 column density towards high latitudes is apparent, and the typical latitudinal extent of the atmosphere found to be ±40° at half-maximum. The data show moderate diurnal variations of the equatorial atmosphere, which is evidence for a partially sublimation-supported atmospheric component. Compared to local noon, factor of 2 lower densities are observed ∼40° before and ∼80° after noon. Best-fit gas temperatures range from 150 to 220 K, with a weighted mean value of 170 ± 20 K, which should represent the column-weighted mean kinetic temperature of Io’s atmosphere. Finally, although the data include clear thermal emission due to Pillan (in outburst in July 2008) and Loki, no detectable enhancements in the SO 2 atmosphere above these volcanic regions are found, with an upper limit of 4 × 10 16 cm −2 at Pillan and 1 × 10 17 cm −2 at Loki. [ABSTRACT FROM AUTHOR]

The slow nova V2676 Oph was unique in that both C2 and CN molecules were observed during its early phase around the visual brightness maximum. The absorption bands of these molecules were detected using spectroscopic techniques and disappeared within several days. The formation of CO was followed by dust formation, which was confirmed via observations in the latter phase of the nova. The formation of molecules is critically important in understanding the origin of dust grains in novae; however, the formation mechanism of C2 and CN molecules in the early phase of novae remain unclear. Here we report optical spectroscopic observations of the dust-forming nova V2676 Oph in the early phase, and we use these data in addition to spectroscopic observations reported previously to discuss the origin of diatomic molecules in the nova. We conclude that C2 and CN molecules formed in the nova outflow when the outer gas envelope cooled sufficiently and that they survived for more than 2 days but less than 7 days in the nova outflow. [ABSTRACT FROM AUTHOR]

We report on early results from a pilot program searching for metal-poor stars with LAMOST and follow-up high-resolution observation acquired with the MIKE spectrograph attached to the Magellan II telescope. We performed detailed abundance analysis for eight objects with iron abundances [Fe/H] < -2.0, including five extremely metal-poor (EMP; [Fe/H] < -3.0) stars with two having [Fe/H] < -3.5. Among these objects, three are newly discovered EMP stars, one of which is confirmed for the first time with high-resolution spectral observations. Three program stars are regarded as carbon-enhanced metal-poor (CEMP) stars, including two stars with no enhancement in their neutron-capture elements, which thus possibly belong to the class of CEMP-no stars; one of these objects also exhibits significant enhancement in nitrogen, and is thus a potential carbon and nitrogen-enhanced metal-poor star. The [X/Fe] ratios of the sample stars generally agree with those reported in the literature for other metal-poor stars in the same [Fe/H] range. We also compared the abundance patterns of individual program stars with the average abundance pattern of metal-poor stars and find only one chemically peculiar object with abundances of at least two elements (other than C and N) showing deviations larger than 0.5 dex. The distribution of [Sr/Ba] versus [Ba/H] agrees that an additional nucleosynthesis mechanism is needed aside from a single r-process. Two program stars with extremely low abundances of Sr and Ba support the prospect that both main and weak r-processes may have operated during the early phase of Galactic chemical evolution. The distribution of [C/N] shows that there are two groups of carbon-normal giants with different degrees of mixing. However, it is difficult to explain the observed behavior of the [C/N] of the nitrogen-enhanced unevolved stars based on current data. [ABSTRACT FROM AUTHOR]

Long-slit spectroscopy results of the dwarf spiral galaxy IC 1727, which is interacting with NGC 672, are presented. The extinction, excitation, density and shocks throughout the galaxy are studied, as well as the oxygen abundances of a total of 22 H ii regions. The interstellar medium of this galaxy is very perturbed, with high values of the [S ii]/Hα ratio and high excitation values throughout the galaxy (inside the H ii regions and in the diffuse ionized gas). Such values might be an indication of strong perturbations resulting from the interaction between IC 1727 and NGC 672. Shocks are the second source of ionization of the diffuse ionized gas, after leaking photons from H ii regions. The chemical abundance of this galaxy is well below solar and closer to the values of the Large Magellanic Cloud. The abundances differ between the various H ii regions of the galaxy, as observed in other spiral galaxies. [ABSTRACT FROM AUTHOR]

Context. The Li-rich turn-off star recently discovered in the old, metal-poor globular cluster NGC 6397 could represent the smoking gun for some fundamental, but very rare episode of Li enrichment in globular clusters and in the early Galaxy. Aims. We aim to understand the nature of the Li enrichment by performing a spectroscopic analysis of the star, in particular of its beryllium (Be) abundance, and by investigating its binary nature. Methods. We used the VLT/UVES spectrograph to observe the near UV region where the Be ii resonance doublet and the NH bands are located. We also re-analyzed an archival Magellan/MIKE spectra for C and O abundance determination. Results. We could not detect the Be ii lines and derive an upper limit of log(Be/H) < -12.2 that is consistent with the Be observed in other stars of the cluster. We could detect a weak G-band, which implies a mild carbon enhancement [C/Fe]+0.4 ± 0.2. We could not detect the UV NH band, showing that this star is less N-enhanced than other stars of the cluster, and we derive an upper limit [N/Fe] < 0.0. For oxygen we could not convincingly detect any of the near UV OH lines, which implies that oxygen cannot be strongly enhanced in this star. This is consistent with the detection of the strongest line of the Oi triplet at 777 nm, which is contaminated by telluric absorptions but is consistent with [O/Fe] ~ 0.5. Combining the UVES and Mike data, we could not detect any variation in the radial velocity greater than 0.95 kms-1 over 8 years. Conclusions. The chemical composition of the star strongly resembles that of "first generation" NGC 6397 stars, with the huge Li as the only deviating abundance. Not detecting Be rules out two possible explanations of the Li overabundance: capture of a substellar body and spallation caused by a nearby type II SNe. Discrepancies are also found with respect to other accretion scenarios, except for contamination by the ejecta of a star that has undergone the RGB Li-flash. This is at present the most likely possibility for explaining the extraordinary Li enrichment of this star. [ABSTRACT FROM AUTHOR]

Context. Most spectroscopic studies of planetary nebulae (PNe) are based on data from specific parts of the objects. Considering the high complexity of their morphological structures, integrated or average values across an observed region can only provide limited information of their ionic, density, and temperature structures. Aims. We investigate the spatial variation of the physical and chemical properties of NGC 6302, a high-ionization PNe, with a complex bipolar structure. Methods. Spatially resolved long-slit spectroscopic data were obtained from 11 parallel and equally spaced directions over the nebula. Maps of emission line fluxes, line ratios, electron temperature Te, electron density Ne, and ionic abundances (He+, He2+, N0, N+, O0, O+, O2+, S+, S2+, Ne2+, Ar2+, Ar3+, and Ar4+ relative to H+) were constructed with a spatial resolution of 1.45" x1" for a large portion of the nebula over an area of 11" x 250" . Electron densities were estimated from the [S ii]λ 6716/λ 6731 and [Ar iv]λ 4711/λ 4740 line ratios, and electron temperatures were estimated from the [O iii](λ 4959 + λ 5007)/λ 4363 and [Nii](λ 6548 + λ 6584)/λ 5755 ratios. Integrated spectra were also obtained and 142 lines were identified. Results. The electron density maps show a peaked distribution, with the densest area at the circumstellar region, reaching Ne ≈ 40 000 cm-3, and decreasing to Ne ⩽ 1000 cm-3 at the lobes. Knots were observed in the Ne(S ii) map, with 2000 cm-3 < Ne < 3000 cm-3. The Ne(Ar iv) map suggests the presence of an inner region with Ne ≈ 20 000 cm-3 that extends from the center through the east lobe. A homogeneous temperature distribution was found for both Te(O iii) and Te(N ii). Small temperature fluctuations on the plane of the sky of t2s (N ii) = 0.0071 and t2s (O iii) = 0.0043 were estimated. Conclusions. In general, the total abundances obtained are similar to the maximum found in the ionic abundance maps of the dominant ionic species. This demonstrates the potential of spatially resolved abundance studies for establishing lower limits of the total abundances based on ionic abundances, for checking the ionization correlation factors, and in some cases, for determining the total abundances directly from maps of ionic abundances. [ABSTRACT FROM AUTHOR]

We present the abundances of N in a sample of 62 stars on the red giant branch (RGB) in the peculiar globular cluster NGC 1851. The values of [N/Fe] ratio were obtained by comparing the flux measured in the observed spectra with that from synthetic spectra for up to about 15 features of CN. This is the first time that N abundances are obtained for such a large sample of RGB stars from mediumresolution spectroscopy in this cluster. With these abundances, we provide chemical tagging of the split RGB found from several studies in NGC 1851. The secondary reddest sequence on the RGB is populated almost exclusively by N-rich stars, confirming our previous suggestion based on Strömgren magnitudes and colours. These giants are also, on average, enriched in s-process elements such as Ba, and are likely the results of pollution from low-mass stars that experienced episodes of third dredge-up in the asymptotic giant branch phase. [ABSTRACT FROM AUTHOR]

Aims. Trumpler 20 is an open cluster located at low Galactic longitude, just beyond the great Carina spiral arm, and whose metallicity and fundamental parameters were very poorly known until now. As it is most likely a rare example of an old, rich open cluster - possibly a twin of NGC 7789 - it is useful to characterize it. To this end, we determine here the abundance of several elements and their ratios in a sample of stars in the clump of Trumpler 20. Methods. We present high-resolution spectroscopy of eight clump stars. Based on their radial velocities, we identify six bona fide cluster members, and for five of them (the sixth being a fast rotator) we perform a detailed abundance analysis. Results. We find that Trumpler 20 is slightly more metal-rich than the Sun, having [Fe/H] = +0.09 ± 0.10. The abundance ratios of α-elements are generally solar. In line with recent studies of clusters as old as Trumpler 20, Ba is overabundant compared to the Sun. Our analysis of the iron-peak elements (Cr and Ni) does not reveal anything anomalous. Based on these results, we re-estimate the cluster age to be 1.5+0.2 -0.1 Gyr. Its distance to the Galactic centre turns out to be 7.3 kpc. With this distance and metallicity, Trumpler 20 fits fairly well in the metallicity gradient for the Galactic inner disc. Conclusions. With this new study, the characterization of Trumpler 20 is now on much more solid ground. Further studies should focus on the estimate of the binary fraction and on its main sequence membership. [ABSTRACT FROM AUTHOR]

Context. AM Canum Venaticorum stars are close, interacting binary systems with a white dwarf primary surrounded by a helium-dominated accretion disk. Because of the short orbital periods, the unseen secondary must be compact, too. Different evolutionary scenarios for the formation of these systems resulting in different kinds of secondaries are possible. Aims. Quantitative spectral analyses of accretion-disk spectra can reveal the nature of the secondary. We investigate a particular AM CVn system, discovered recently by the Palomar Transient Factory, PTF 09hpk. It is the only known AM CVn star exhibiting unambiguously both outbursts and superoutbursts. We characterize the accretion disk in quiescence and determine abundances of trace elements. Methods. We calculated line-blanketed nonlocal thermodynamic equilibrium (non-LTE) models and computed accretion-disk spectra by self-consistent solution of radiative transfer and vertical structure equations. These are compared to optical spectra taken during quiescence. Results. In quiescence, the disk has a uniform effective temperature of 6000 K. An optically thin boundary layer causes the observed He II λ 4686 Å emission feature. The disk around the massive white dwarf primary (1.2 M☉) is dominated by helium and is strongly hydrogen-deficient (<-5 dex relative to the solar value). For heavy elements (C, N, O, Mg, Si, Fe), we find moderate to strong subsolar abundances, with depletions down to -2.5 dex for iron. The N/O ratio is >10. Conclusions. According to the high N/O ratio, the secondary of PTF 09hpk is either a helium white dwarf or a helium star. The low metallicity points to a halo origin of the system or it might be the consequence of heavy-metal sedimentation if the secondary is an old, low-mass helium white dwarf. [ABSTRACT FROM AUTHOR]

We report our spectroscopic investigation of the transiting ice giant GJ 3470b's atmospheric transmission, and the first results of extrasolar planet observations from the new Keck/MOSFIRE spectrograph. We measure a planet/star radius ratio of 0:0789-0:0019 +0:0021 in a bandpass from 2.09-2.36 μm and in six narrower bands across this wavelength range. When combined with existing broadband photometry, these measurements rule out cloud-free atmospheres in chemical equilibrium assuming either solar abundances (5.4σ confidence) or a moderate level of metal enrichment (50× solar abundances, 3.8σ), confirming previous results that such models are not representative for cool, low-mass, externally irradiated extrasolar planets. Current measurements are consistent with a flat transmission spectrum, which suggests that the atmosphere is explained by high-altitude clouds and haze, disequilibrium chemistry, unexpected abundance patterns, or the atmosphere is extremely metal-rich (≳200× solar). Because GJ 3470b's low bulk density sets an upper limit on the planet's atmospheric enrichment of ≲300× solar, the atmospheric mean molecular weight must be ≲9. Thus, if the atmosphere is cloud-free its spectral features should be detectable with future observations. Transit observations at shorter wavelengths will provide the best opportunity to discriminate between plausible scenarios. We obtained optical spectroscopy with the MOS spectrograph, but these observations exhibit large systematic uncertainties owing to thin, persistent cirrus conditions. Finally, we also provide the first detailed look at the steps necessary for well-calibrated MOSFIRE observations, and provide advice for future observations with this instrument. [ABSTRACT FROM AUTHOR]

Context. Precise stellar parameters are crucial in exoplanet research for correctly determining the planetary parameters. For stars hosting a transiting planet, determining the planetary mass and radius depends on the stellar mass and radius, which in turn depend on the atmospheric stellar parameters. Different methods can provide different results, which leads to different planet characteristics. Aims. In this paper, we use a uniform method to spectroscopically derive stellar atmospheric parameters, chemical abundances, stellar masses, and stellar radii for a sample of 90 transit hosts. Surface gravities are also derived photometrically using the stellar density as derived from the light curve. We study the effect of using these different surface gravities on the determination of the chemical abundances and the stellar mass and radius. Methods. A spectroscopic analysis based on Kurucz models in local thermodynamical equilibrium was performed through theMOOG code to derive the atmospheric parameters and the chemical abundances. The photometric surface gravity was determined through isochrone fitting and the use of the stellar density, directly determined from the light curve. Stellar masses and radii are determined through calibration formulae. Results. Spectroscopic and photometric surface gravities differ, but this has very little effect on the precise determination of the stellar mass in our spectroscopic analysis. The stellar radius, and hence the planetary radius, is most affected by the surface gravity discrepancies. For the chemical abundances, the difference is, as expected, only noticeable for the abundances derived from analyzing lines of ionized species. [ABSTRACT FROM AUTHOR]

Context. The large amount of spectra obtained during the epoch of extensive spectroscopic surveys of Galactic stars needs the development of automatic procedures to derive their atmospheric parameters and individual element abundances. Aims. Starting from the widely-used code MOOG by C. Sneden, we have developed a new procedure to determine atmospheric parameters and abundances in a fully automatic way. The code FAMA (Fast Automatic MOOG Analysis) is presented describing its approach to derive atmospheric stellar parameters and element abundances. The code, freely distributed, is written in Perl and can be used on di erent platforms. Methods. The aim of FAMA is to render the computation of the atmospheric parameters and abundances of a large number of stars using measurements of equivalent widths (EWs) as automatic and as independent of any subjective approach as possible. It is based on the simultaneous search for three equilibria: excitation equilibrium, ionization balance, and the relationship between log n(Fe i) and the reduced EWs. FAMA also evaluates the statistical errors on individual element abundances and errors due to the uncertainties in the stellar parameters. The convergence criteria are not fixed "a priori" but are based on the quality of the spectra. Results. In this paper we present tests performed on the solar spectrum EWs that assess the method's dependency on the initial parameters and we analyze a sample of stars observed in Galactic open and globular clusters. [ABSTRACT FROM AUTHOR]

Getting spectra at good signal-to-noise ratios takes orders of magnitudes more time than photometric observations. Building on the technique developed for photometric redshift estimation of galaxies, we develop and demonstrate a nonparametric photometric method for estimating the chemical composition of Galactic stars. We investigate the efficiency of our method using spectroscopically determined stellar metallicities from SDSS DR7. The technique is generic in the sense that it is not restricted to certain stellar types or stellar parameter ranges and makes it possible to obtain metallicities and error estimates for a much larger sample than spectroscopic surveys would allow. We find that our method performs well, especially for brighter stars and higher metallicities and, in contrast to many other techniques, we are able to reliably estimate the error of the predicted metallicities. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The double-lined spectroscopic binary HD 104237 (DX Cha) is part of a complex system of some half-dozen nearby young stars. We report a significant change from an orbit for the SB2 system derived from 1999–2000 observations. We obtain abundances from the primary and secondary spectra. The abundance analysis uses both detailed spectral synthesis and determinations based on equivalent widths of weak absorption lines with Wλ typically <25 mÅ. Abundances are derived for 25 elements in the primary, and 17 elements in the secondary. Apart from lithium and zirconium, abundances do not depart significantly from solar. Lithium may be marginally enhanced with respect to the meteoritic value in the primary. It somewhat depleted in the secondary. The emission-line spectrum is typical of Herbig Ae stars. We compare and contrast the spectra of the HD 104237 primary and two other Herbig Ae stars with low v sin (i), HD 101412 and HD 190073. [ABSTRACT FROM AUTHOR]

In this paper, we present a detailed spectroscopic analysis of the suspected marginal Am star HD 71297. Our goal is to test the accuracy of two different approaches to determine the atmospheric parameters: effective temperature, gravity, projected rotational velocity and chemical abundances. The methods used in this paper are: classical spectral synthesis and the Versatile Wavelength Analysis (vwa) software.Since our star is bright and very close to the Sun, we were able to determine its effective temperature and gravity directly through photometric, interferometric and parallax measurements. The values found were taken as reference to which we compare the values derived by spectroscopic methods. Our analysis leads us to conclude that the spectroscopic methods considered in this study to derive fundamental parameters give consistent results, if we consider all the sources of experimental errors, that have been discussed in the text. In addition, our study shows that the spectroscopic results are quite as accurate as those derived from direct measurements.As for the specific object analysed here, according to our analysis, HD 71297 has chemical abundances not compatible with the previous spectral classification. We found moderate underabundances of carbon, sodium, magnesium and iron-peak elements, while oxygen, aluminium, silicon, sulphur and heavy elements (Z ≥ 39) are solar in content. This chemical pattern has been confirmed by the calculations performed with both methods. [ABSTRACT FROM AUTHOR]

The properties of the stellar population of the unusual object NGC 2419 are studied; this is the most distant high-mass globular cluster of the Galaxy's outer halo, and a spectrum taken with the 1.93-m telescope of the Haute Provence Observatory displays elemental abundance anomalies. Since traditional high-resolution spectroscopicmethods are applicable to bright stars only, spectroscopic information for the cluster's stellar population as a whole, integrated along the spectrograph slit placed in various positions, is used. Population synthesis is carried out for the spectrum of NGC 2419 using synthetic spectra calculated from a grid of stellar model atmospheres, based on the theoretical isochrone from the literature that best fits the color-magnitude diagram of the cluster. The derived age (12.6 billion years), metallicity ([Fe/H] = −2.25 dex), and abundances of helium ( Y = 0.26) and other chemical elements (a total of 14) are in a good qualitative agreement with estimates from the literature made from high-resolution spectra of eight red giants in the cluster. The influence on the spectrum of deviations from local thermodynamic equilibrium is considered for several elements. The derived abundance of α-elements ([ α/Fe] = 0.13 dex, as the mean of [O/Fe], [Mg/Fe], and [Ca/Fe]) differs from the mean value in the literature ([ α/Fe] = 0.4 for the eight brightest red giants) and may be explained by recently discovered in NGC2419 large [a/Fe] dispersion. Further studies of the integrated properties of the stellar population in NGC 2419 using higher-resolution spectrographs in various wavelength ranges should help improve our understanding of the cluster's chemical anomalies. [ABSTRACT FROM AUTHOR]

We present results from Keck/NIRSPEC and Magellan/MMIRS follow-up spectroscopy of Lyα emitters (LAEs) at z = 2.2 identified in our Subaru narrowband survey. We successfully detect Hα emission from seven LAEs, and perform a detailed analysis of six LAEs free from active galactic nucleus activity, two out of which, CDFS-3865 and COSMOS-30679, have [OII] and [OIII] line detections. They are the first [OII]-detected LAEs at high-z, and their [OIII]/[OII] ratios and R23-indices provide the first simultaneous determinations of ionization parameter and oxygen abundance for LAEs. CDFS-3865 has a very high ionization parameter (qion = 2.5+1.7 -0.8 × 108 cm s-1) and a low oxygen abundance (12 + log(O/H) = 7.84+0.24 -0.25) in contrast with moderate values of other high-z galaxies such as Lyman break galaxies (LBGs). COSMOS-30679 also possesses a relatively high ionization parameter (qion = 8+10 -4 × 107 cm s-1) and a low oxygen abundance (12 + log(O/H) = 8.18+0.28 -0.28). Both LAEs appear to fall below the mass-metallicity relation of z ∼ 2 LBGs. Similarly, a low metallicity of 12 + log(O/H) < 8.4 is independently indicated for typical LAEs from a composite spectrum and the [NII]/Hα index. Such high ionization parameters and low oxygen abundances can be found in local star-forming galaxies, but this extreme local population occupies only∼0.06% of the Sloan Digital Sky Survey spectroscopic galaxy sample with a number density ∼100 times smaller than that of LAEs. With their high ionization parameters and low oxygen abundances, LAEs would represent an early stage of galaxy formation dominated by massive stars in compact star-forming regions. High-qion galaxies like LAEs would produce ionizing photons efficiently with a high escape fraction achieved by density-bounded Hii regions, which would significantly contribute to cosmic reionization at z > 6. [ABSTRACT FROM AUTHOR]

We present a detailed abundance study based on spectroscopic data obtained with HARPS of two solar-analogue main targets for the asteroseismology programme of the CoRoT satellite: HD42618 and HD43587. The atmospheric parameters and chemical composition are accurately determined through a fully differential analysis with respect to the Sun observed with the same instrumental set-up. Several sources of systematic errors largely cancel out with this approach, which allows us to narrow down the 1-σ error bars to typically 20 K in effective temperature, 0.04 dex in surface gravity, and less than 0.05 dex in the elemental abundances. Although HD42618 fulfils many requirements for being classified as a solar twin, its slight deficiency in metals and its possibly younger age indicate that, strictly speaking, it does not belong to this class of objects. On the other hand, HD43587 is slightly more massive and evolved. In addition, marked differences are found in the amount of lithium present in the photospheres of these two stars, which might reveal different mixing properties in their interiors. These results will put tight constraints on the forthcoming theoretical modelling of their solar-like oscillations and contribute to increase our knowledge of the fundamental parameters and internal structure of stars similar to our Sun. [ABSTRACT FROM AUTHOR]

Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from −10.5 to +4.8 d relative to B-band maximum. The photospheric near-UV spectra are excellent diagnostics of the iron-group abundances in the outer layers of the ejecta, particularly those at very early times. Using the method of ‘Abundance Tomography’ we derive iron-group abundances in SN 2010jn with a precision better than in any previously studied SN Ia. Optimum fits to the data can be obtained if burned material is present even at high velocities, including significant mass fractions of iron-group elements. This is consistent with the slow decline rate (or high ‘stretch’) of the light curve of SN 2010jn, and consistent with the results of delayed-detonation models. Early-phase UV spectra and detailed time-dependent series of further SNe Ia offer a promising probe of the nature of the SN Ia mechanism. [ABSTRACT FROM PUBLISHER]

ABSTRACT We present stellar parameters and abundances of 11 elements (Li, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni and Zn) of 13 F6-K2 main-sequence stars in the young groups AB Doradus, Carina Near and Ursa Major. The exoplanet-host star ι Horologii is also analysed. The three young associations have lithium abundance consistent with their age. All other elements show solar abundances. The three groups are characterized by a small scatter in all abundances, with mean [Fe/H] values of 0.10 (σ = 0.03), 0.08 (σ = 0.05) and 0.01 (σ = 0.03) dex for AB Doradus, Carina Near and Ursa Major, respectively. The distribution of elemental abundances appears congruent with the chemical pattern of the Galactic thin disc in the solar vicinity, as found for other young groups. This means that the metallicity distribution of nearby young stars, targets of direct-imaging planet-search surveys, is different from that of old, field solar-type stars, i.e. the typical targets of radial velocity surveys. The young planet-host star ι Horologii shows a lithium abundance lower than that found for the young association members. It is found to have a slightly super-solar iron abundance ([Fe/H] = 0.16 ± 0.09), while all [X/Fe] ratios are similar to the solar values. Its elemental abundances are close to those of the Hyades cluster derived from the literature, which seems to reinforce the idea of a possible common origin with the primordial cluster. [ABSTRACT FROM AUTHOR]

ABSTRACT Standard big bang nucleosynthesis (BBN) at the baryon density determined by the microwave anisotropy spectrum predicts an excess of 7Li compared to observations by a factor of 4-5. In contrast, BBN predictions for D/H are somewhat below (but within 2σ of) the weighted mean of observationally determined values from quasar absorption systems. Solutions to the 7Li problem which alter the nuclear processes during or subsequent to BBN often lead to a significant increase in the deuterium abundance consistent with the highest values of D/H seen in absorption systems. Furthermore, the observed D/H abundances show considerable dispersion. Here, we argue that those systems with D/H ≃ 4 × 10−5 may be more representative of the primordial abundance and as a consequence, those systems with lower D/H would necessarily have been subject to local processes of deuterium destruction. This can be accounted for by models of cosmic chemical evolution able to destroy in situ deuterium due to the fragility of this isotope. [ABSTRACT FROM AUTHOR]