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- ID:
- ivo://CDS.VizieR/J/AZh/82/453
- Title:
- Catalogue of spectroscopic abundances in stars
- Short Name:
- J/AZh/82/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We submit the compiled catalogue of effective temperatures, surface gravities, abundances of iron and magnesium, distances, velocity components, and orbital parameters for stars of solar vicinity. Atmospheric parameters and iron abundances was determined by averaging of published values, which was found from synthetic analysis of high resolution spectra on the basis of 1809 determination from 31 publications. Relative magnesium abundances for 876 dwarfs and subgiants were determined as a result of three-step iteration procedure of averaging with giving weight to each publication and each individual determination. The systematic shifts for each scale relative to reduced main scale was taken into account. We suppose that survey completeness of publications with volume more than 5 stars up to December 2003 is 90%. Spatial velocity components for most majority stars were determined on the stellar data from present day high-precision observations. Galactic orbital parameter were calculated using the Galactic model, which includes a spherical bulge, disk, and extended massive halo.
- ID:
- ivo://CDS.VizieR/III/121
- Title:
- Catalogue of stellar abundances
- Short Name:
- III/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue, compiled at the Torun Observatory, contains the published abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A121
- Title:
- CaT/[Fe/H] calibration for Galactic bulge stars
- Short Name:
- J/A+A/580/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new calibration of the calcium II triplet equivalent widths versus [Fe/H], constructed upon K giant stars in the Galactic bulge. This calibration will be used to derive iron abundances for the targets of the GIBS survey, and is in general especially well suited for solar and supersolar metallicity giants, which are typical of external massive galaxies. To obtain the calibration, about 150 bulge K giants were observed with the GIRAFFE spectrograph at the VLT with a resolution of R~20000 and at R~6000. In the first case, the spectra allowed us to directly determine the Fe abundances from several unblended Fe lines, deriving what we call here high-resolution [Fe/H] measurements. The low-resolution spectra allowed us to measure equivalent widths of the two strongest lines of the near-infrared calcium II triplet at 8542 and 8662{AA}. By comparing the two measurements, we derived a relation between calcium equivalent widths and [Fe/H] that is linear over the metallicity range probed here, -1<[Fe/H]<+0.7. By adding a small second-order correction based on literature globular cluster data, we derived the unique calibration equation [Fe/H]_CaT_=-3.150+0.432W'+0.006W'^2^, with an rms dispersion of 0.197dex, valid across the whole metallicity range -2.3<[Fe/H]<+0.7.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/15
- Title:
- CCCP: Carina's diffuse X-ray emission
- Short Name:
- J/ApJS/194/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 1.42deg^2^ mosaic of diffuse X-ray emission in the Great Nebula in Carina from the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer camera. After removing >14000 X-ray point sources from the field, we smooth the remaining unresolved emission, tessellate it into segments of similar apparent surface brightness, and perform X-ray spectral fitting on those tessellates to infer the intrinsic properties of the X-ray-emitting plasma. By modeling faint resolved point sources, we estimate the contribution to the extended X-ray emission from unresolved point sources and show that the vast majority of Carina's unresolved X-ray emission is truly diffuse. Line-like correlated residuals in the X-ray spectral fits suggest that substantial X-ray emission is generated by charge exchange at the interfaces between Carina's hot, rarefied plasma and its many cold neutral pillars, ridges, and clumps.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A12
- Title:
- Cchemical abundances of 6 open cluster stars
- Short Name:
- J/A+A/643/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are excellent tracers of the chemical evolution of the Galactic disc. The spatial distribution of their elemental abundances, through the analysis of high-quality and high-resolution spectra, provides insight into the chemical evolution and mechanisms of element nucleosynthesis in regions characterised by different conditions (e.g. star formation efficiency and metallicity). In the framework of the Stellar Population Astrophysics (SPA) project, we present new observations and spectral analysis of four sparsely studied open clusters located in the solar neighbourhood, namely Collinder 350, Gulliver 51, NGC 7044, and Ruprecht 171. We exploit the HARPS-N spectrograph at the TNG telescope to acquire high-resolution optical spectra for 15 member stars of four clusters. We derive stellar parameters (Teff, logg, [Fe/H] and {xi) using both the equivalent width (EW) analysis and the spectral fitting technique. We compute elemental abundances for light, {alpha}-, iron-peak, and n-capture elements using the EW measurement approach. We investigate the origin of the correlation between metallicity and stellar parameters derived with the EW method for the coolest stars of the sample (Teff<4300K). The correlation is likely due to the challenging continuum setting and to a general inaccuracy of model atmospheres used to reproduce the conditions of very cool giant stars. We locate the properties of our clusters in the radial distributions of metallicity and abundance ratios, comparing our results with clusters from the Gaia-ESO and APOGEE surveys. We present the [X/Fe]-[Fe/H] and [X/Fe]-RGC trends for elements in common between the two surveys. Finally, we derive the C and Li abundances as a function of the evolutionary phase and compare them with theoretical models. The SPA survey, with its high-resolution spectra, allows us to fully characterise the chemistry of nearby clusters. With a single set of spectra, we provide chemical abundances for a variety of chemical elements, which are comparable to those obtained in two of the largest surveys combined. The metallicities and abundance ratios of our clusters fit very well in the radial distributions defined by the recent literature, reinforcing the importance of star clusters to outline the spatial distribution of abundances in our Galaxy. Moreover, the abundances of C and Li, modified by stellar evolution during the giant phase, agree with evolutionary prescriptions (rotation-induced mixing) for their masses and metallicities.
- ID:
- ivo://CDS.VizieR/J/ApJ/747/102
- Title:
- ^12^C/^13^C ratio for 18 galactic R CrB stars
- Short Name:
- J/ApJ/747/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C_2_ Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C_2_ bands are used to derive the ^12^C abundance, and the (1, 0) ^12^C^13^C band to determine the ^12^C/^13^C ratios. The carbon abundance derived from the C_2_ Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He=0.1%) to 10.5 (C/He=10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the "carbon problem." In principle, the carbon abundances obtained from C_2_ Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C_2_ bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C_2_ carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the ^12^C/^13^C ratios are discussed in light of the double degenerate and the final flash scenarios.
- ID:
- ivo://CDS.VizieR/J/ApJ/678/985
- Title:
- c2d Spitzer survey of interstellar ices. I.
- Short Name:
- J/ApJ/678/985
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study the physical and chemical evolution of ices in solar-mass systems, a spectral survey is conducted of a sample of 41 low-luminosity YSOs (L~0.1-10L_{sun}_) using 3-38um Spitzer and ground-based spectra. The sample is complemented with previously published Spitzer spectra of background stars and with ISO spectra of well-studied massive YSOs (L~10^5^L_{sun}_). The long-known 6.0 and 6.85um bands are detected toward all sources, with the Class 0-type YSOs showing the deepest bands ever observed. The 6.0um band is often deeper than expected from the bending mode of pure solid H_2_O. The additional 5-7um absorption consists of five independent components, which, by comparison to laboratory studies, must be from at least eight different carriers. Much of this absorption is due to simple species likely formed by grain surface chemistry, at abundances of 1%-30% for CH_3_OH, 3%-8% for NH_3_, 1%-5% for HCOOH, ~6% for H_2_CO, and ~0.3% for HCOO- relative to solid H_2_O. The 6.85um band has one or two carriers, of which one may be less volatile than H_2_O. Its carrier(s) formed early in the molecular cloud evolution and do not survive in the diffuse ISM. If an NH_4_^+^ -containing salt is the carrier, its abundance relative to solid H_2_O is ~7%, demonstrating the efficiency of low-temperature acid-base chemistry or cosmic-ray-induced reactions. Possible origins are discussed for enigmatic, very broad absorption between 5 and 8um. Finally, the same ices are observed toward massive and low-mass YSOs, indicating that processing by internal UV radiation fields is a minor factor in their early chemical evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1362
- Title:
- Century Survey Galactic Halo Project. I.
- Short Name:
- J/AJ/126/1362
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Century Survey Galactic Halo Project is a photometric and spectroscopic survey from which we select relatively blue stars (V-R<0.30mag) as probes of the Milky Way halo. The survey strip spans the range of Galactic latitude 35{deg}<b<88{deg}, allowing us to study the nature of populations of stars and their systematic motions as a function of Galactic latitude. One of our primary goals is to use blue horizontal-branch stars to trace potential star streams in the halo, and to test the hierarchical model for the formation of the Galaxy. In this paper we discuss spectroscopy and multipassband photometry for a sample of 764 blue stars in the Century Survey region. Our sample consists predominantly of A- and F-type stars. We describe our techniques for determination of radial velocities, effective temperatures, metallicities, and surface gravities. Based on these measurements, we derive distance estimates by comparison with a set of calibrated isochrones. We devote special attention to the classification of blue horizontal-branch stars, and compare the results obtained from the application of the techniques of Kinman et al. 1994, Cat. <J/AJ/108/1722>, Wilhelm et al. (1999, Cat. <J/AJ/117/2308>), and Clewley et al. (2002MNRAS.337...87C). We identify 55 blue horizontal-branch stars. Our large sample of stars also uncovers a number of unusual objects, including three carbon-enhanced stars, a late B-type star located 0.8kpc above the Galactic plane, and a DZ white dwarf.
- ID:
- ivo://CDS.VizieR/J/AJ/156/171
- Title:
- Cepheid abund.: multiphase results & spatial gradients
- Short Name:
- J/AJ/156/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parameters and abundances have been derived for 435 Cepheids based on an analysis of 1127 spectra. Results from five or more phases are available for 52 of the program stars. The latter set of stars span periods between 1.5 and 68 days. The parameters and abundances show excellent consistency across phase. For iron, the average range in the determined abundance is 0.11 from these 52 stars. For 163 stars with more than one phase available the average range is 0.07. The variation in effective temperature tracks well with phase, as does the total broadening velocity. The gravity and microturbulent velocity follow phase, but with less variation and regularity. Abundance gradients have been derived using Gaia DR2 (Cat. I/345) parallax data, as well as Bayesian distance estimates based upon Gaia DR2 from Bailer-Jones et al. (2018, Cat. I/347). The abundance gradient derived for iron is d[Fe/H]/dR=-0.05 dex/kpc, similar to gradients derived in previous studies.
