- ID:
- ivo://CDS.VizieR/J/ApJ/711/619
- Title:
- {alpha}-element abundances in galactic PNe
- Short Name:
- J/ApJ/711/619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present emission line strengths, abundances, and element ratios (X/O for Ne, S, Cl, and Ar) for a sample of 38 Galactic disk planetary nebulae (PNe) consisting primarily of Peimbert classification Type I. Spectrophotometry for these PNe incorporates an extended optical/near-IR range of 3600-9600{AA} including the [SIII] lines at 9069{AA} and 9532{AA}, setting this relatively large sample apart from typical spectral coverage. We have utilized Emission Line Spectrum Analyzer, a five-level atom abundance routine, to determine Te, Ne, ionization correction factors, and total element abundances, thereby continuing our work toward a uniformly processed set of data. With a compilation of data from >120 Milky Way PNe, we present results from our most recent analysis of abundance patterns in Galactic disk PNe. With a wide range of metallicities, galactocentric distances, and both Type I and non-Type I objects, we have examined the alpha elements against HII regions and blue compact galaxies (H2BCGs) to discern signatures of depletion or enhancement in PNe progenitor stars, particularly the destruction or production of O and Ne.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/580/A17
- Title:
- {alpha}-element abundances of Cepheid stars
- Short Name:
- J/A+A/580/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new homogeneous measurements of Na, Al, and three alpha-elements (Mg, Si, Ca) for 75 Galactic Cepheids, complemented with Cepheid abundances available in the literature, for a total of 439 stars. The abundances are based on high spectral resolution (R~38000) and high signal-to-noise ratio (S/N~50-300) spectra collected with UVES at ESO VLT. Special attention was given to providing a homogeneous abundance scale for these five elements plus iron. In addition, accurate Galactocentric distances (RG) based on near-infrared photometry are also available for all the Cepheids in the sample. We found that these five elements display well-defined linear radial gradients and modest standard deviations over the entire range of RG. The [element/Fe] abundance ratios are constant across the entire thin disk and over the entire period range; only the Ca radial distribution shows marginal evidence of slopes. These results indicate that the chemical enrichment history of iron and of the quoted elements has been quite similar across the four quadrants of the Galactic thin disk, and very homogenous within the range in age covered by the Cepheids (~10-300Myr). Finally, we also find that Cepheid abundances agree with similar abundances for thin and thick disk dwarf stars, and they follow the typical Mg-Al and Na-O correlations.
- ID:
- ivo://CDS.VizieR/J/ApJS/160/176
- Title:
- alpha-enhanced integrated Lick/IDS spectral indices
- Short Name:
- J/ApJS/160/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- All 25 Lick/IDS spectral indices have been computed for the integrated light of simple stellar populations over broad ranges of age and metallicity and with effects from horizontal-branch stars fully implemented. Our models employ {alpha}-enhanced isochrones at the sub-solar metallicity regime, but solar-scaled ones at solar and super-solar metallicity. We have also employed the updated response functions of Houdashelt et al. (2002AAS...201.1405H) at the solar and super-solar metallicity regime, so that we could assess the light-element enhancement phenomena seen from metal-rich early-type galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/128
- Title:
- alpha & Fe abundances in the giant stellar stream
- Short Name:
- J/ApJ/883/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first measurements of [Fe/H] and [{alpha}/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's giant stellar stream (GSS). The spectroscopic observations, obtained at a projected distance of 17kpc from M31's center, yielded 61 stars with [Fe/H] measurements, including 21 stars with [{alpha}/Fe] measurements, from 112 targets identified as M31 stars. The [Fe/H] measurements confirm the expectation from photometric metallicity estimates that stars in this region of M31's halo are relatively metal rich compared to stars in the Milky Way's inner halo: more than half the stars in the field, including those not associated with kinematically identified substructure, have [Fe/H] abundances >-1.0. The stars in this field are {alpha}-enhanced at lower metallicities, while [{alpha}/Fe] decreases with increasing [Fe/H] above metallicities of [Fe/H]>~-0.9. Three kinematical components have been previously identified in this field: the GSS, a second kinematically cold feature of unknown origin, and M31's kinematically hot halo. We compare probabilistic [Fe/H] and [{alpha}/Fe] distribution functions for each of the components. The GSS and the second kinematically cold feature have very similar abundance distributions, while the halo component is more metal poor. Although the current sample sizes are small, a comparison of the abundances of stars in the GSS field with abundances of M31 halo and dSph stars from the literature indicate that the progenitor of the stream was likely more massive, and experienced a higher efficiency of star formation, than M31's existing dSphs or the dEs NGC147 and NGC185.
- ID:
- ivo://CDS.VizieR/J/other/RAA/16.G10
- Title:
- [alpha/Fe] ratios from LAMOST spectra
- Short Name:
- J/other/RAA/16.G
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The [{alpha}/Fe] ratios in stars are good tracers to probe the formation history of stellar populations and the chemical evolution of the Galaxy. The spectroscopic survey of LAMOST provides a good opportunity to determine [{alpha}/Fe] of millions of stars in the Galaxy. We present a method of measuring the [{alpha}/Fe] ratios from LAMOST spectra using the template-matching technique of the LSP3 pipeline. We use three test samples of stars selected from the ELODIE and MILES libraries, as well as the LEGUE survey to validate our method. Based on the test results, we conclude that our method is valid for measuring [{alpha}/Fe] from low-resolution spectra acquired by the LAMOST survey. Within the range of the stellar parameters Teff=[5000, 7500]K, logg=[1.0, 5.0]dex and [Fe/H]=[-1.5, +0.5]dex, our [{alpha}/Fe] measurements are consistent with values derived from high-resolution spectra, and the accuracy of our [{alpha}/Fe] measurements from LAMOST spectra is better than 0.1dex with spectral signal-to-noise higher than 20.
- ID:
- ivo://CDS.VizieR/J/AN/319/201
- Title:
- Alpha Per cluster low-mass members. I.
- Short Name:
- J/AN/319/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the work of Randich et al. (1996A&A...305..785R) involving a ROSAT raster scan survey of the {alpha} Persei open cluster, we present here the results of a photometric/spectroscopic program examining the possible optical counterparts to a group of 73 X-ray sources in the raster survey which were not matched to catalogued stars. Of the 73 sources investigated, ~40 have an optical counterpart with photometry acceptable for cluster membership and ~20 of these also have radial velocities consistent with membership. We discuss the X-ray properties of these potential new members and why they may not have been identified in earlier membership surveys of this cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/1290
- Title:
- A 2MASS view of the Sgr dSph. VI.
- Short Name:
- J/ApJ/708/1290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution spectroscopic measurements of the abundances of the {alpha} element titanium (Ti) and s-process elements yttrium (Y) and lanthanum (La) for 59 candidate M giant members of the Sagittarius (Sgr) dwarf spheroidal (dSph) + tidal tail system pre-selected on the basis of position and radial velocity (RV). As expected, the majority of these stars show peculiar abundance patterns compared to those of nominal Milky Way (MW) stars, but as a group, the stars form a coherent picture of chemical enrichment of the Sgr dSph from [Fe/H]=-1.4 to solar abundance. Finally, we analyze the chemical abundances of a moving group of M giants among the Sgr leading arm stars at the North Galactic Cap, but having RVs unlike the infalling Sgr leading arm debris there. Through use of "chemical fingerprinting," we conclude that these mostly receding northern hemisphere M giants also are Sgr stars, likely trailing arm debris overlapping the Sgr leading arm in the north.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A162
- Title:
- AMBRE catalogue of sulfur abundances
- Short Name:
- J/A+A/647/A162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sulfur is a volatile chemical element that plays an important role in tracing the chemical evolution of the Milky Way and external galaxies. However, its nucleosynthesis origin and abundance variations in the Galaxy are still unclear because the number of available stellar sulfur abundance measurements is currently rather small. The goal of the present article is to accurately and precisely study the sulfur content of large number of stars located in the solar neighbourhood. We use the parametrisation of thousands of high-resolution stellar spectra provided by the AMBRE Project, and combine it with the automated abundance determination GAUGUIN to derive local thermodynamic equilibrium (LTE) sulfur abundances for 1855 slow-rotating FGK-type stars. This is the largest and most precise catalogue of sulfur abundances published to date. It covers a metallicity domain as high as ~2.5dex starting at [M/H]<~-2.0dex. We find that the sulfur-to-iron abundances ratio is compatible with a plateau-like distribution in the metal-poor regime, and then starts to decrease continuously at [M/H]~-1.0dex. This decrease continues towards negative values for supersolar metallicity stars as recently reported for magnesium and as predicted by Galactic chemical evolution models. Moreover, sulfur-rich stars having metallicities in the range [-1.0,-0.5] have very different kinematical and orbital properties with respect to more metal-rich and sulfur-poor ones. Two disc components, associated with the thin and thick discs, are thus seen independently in kinematics and sulfur abundances. The sulfur radial gradients in the Galactic discs have also been estimated. Finally, the enrichment in sulfur with respect to iron is nicely correlated with stellar ages: older metal-poor stars have higher [S/M] ratios than younger metal-rich ones. This work has confirmed that sulfur is an {alpha}-element that could be considered to explore the Galactic populations properties. For the first time, a chemo-dynamical study from the sulfur abundance point of view, as a stand-alone chemical element, is performed.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A48
- Title:
- AMBRE project. FEROS archived spectra
- Short Name:
- J/A+A/542/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AMBRE Project is a collaboration between the European Southern Observatory (ESO) and the Observatoire de la Cote d'Azur (OCA) that has been established in order to carry out the determination of stellar atmospheric parameters for the archived spectra of four ESO spectrographs. The analysis of the FEROS archived spectra for their stellar parameters (effective temperatures, surface gravities, global metallicities, alpha element to iron ratios and radial velocities) has been completed in the first phase of the AMBRE Project. From the complete ESO:FEROS archive dataset that was received, a total of 21551 scientific spectra have been identified, covering the period 2005 to 2010. These spectra correspond to 6285 stars. The determination of the stellar parameters was carried out using the stellar parameterisation algorithm, MATISSE (MATrix Inversion for Spectral SynthEsis), which has been developed at OCA to be used in the analysis of large scale spectroscopic studies in galactic archaeology. An analysis pipeline has been constructed that integrates spectral normalisation, cleaning and radial velocity correction procedures in order that the FEROS spectra could be analysed automatically with MATISSE to obtain the stellar parameters. The synthetic grid against which the MATISSE analysis is carried out is currently constrained to parameters of FGKM stars only. Stellar atmospheric parameters, effective temperature, surface gravity, metallicity and alpha element abundances, were determined for 6508 (30.2%) of the FEROS archived spectra (~3087 stars). Radial velocities were determined for 11963 (56%) of the archived spectra. 2370 (11%) spectra could not be analysed within the pipeline due to very low signal-to-noise ratios or missing spectral orders. 12673 spectra (58.8%) were analysed in the pipeline but their parameters were discarded based on quality criteria and error analysis determined within the automated process. The majority of these rejected spectra were found to have broad spectral features, as probed both by the direct measurement of the features and cross-correlation function breadths, indicating that they may be hot and/or fast rotating stars, which are not considered within the adopted reference synthetic spectra grid. The current configuration of the synthetic spectra grid is devoted to slow-rotating FGKM stars. Hence non-standard spectra (binaries, chemically peculiar stars etc.) that could not be identified may pollute the analysis.
- ID:
- ivo://CDS.VizieR/J/A+A/560/A9
- Title:
- AMIGA. Revision of the isolation degree
- Short Name:
- J/A+A/560/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the evolution of galaxies, it is necessary to have a reference sample where the effect of the environment is minimized and quantified. In the framework of the AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies), we present a revision of the environment for galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973, Cat. VII/82) using the ninth data release of the Sloan Digital Sky Survey (SDSS-DR9). The aims of this study are to refine the photometric-based AMIGA sample of isolated galaxies and to provide an improvement of the quantification of the isolation degree with respect to previous works, using both photometry and spectroscopy. We developed an automatic method to search for neighbours within a projected area of 1Mpc radius centred on each primary galaxy to revise the CIG isolation criteria introduced by Karachentseva (1973, Cat. VII/82). The local number density at the fifth nearest neighbour and the tidal strength affecting the CIG galaxy were estimated to quantify the isolation degree. Of the 636 CIG galaxies considered in the photometric study, 426 galaxies fulfil the CIG isolation criteria within 1Mpc, taking into account projected neighbours. Of the 411 CIG galaxies considered in the spectroscopic study, 347 galaxies fulfil the CIG isolation criteria when a criterion about redshift difference is added. The available redshifts allow us to reject background neighbours and thus improve the photometric assessment. On average, galaxies in the AMIGA sample show lower values in the local number density and the tidal strength parameters than galaxies in denser environments such as pairs, triplets, compact groups, and clusters. For the first time, the environment and the isolation degree of AMIGA galaxies are quantified using digital data. The use of the SDSS database permits one to identify fainter and smaller-size satellites than in previous AMIGA works. The AMIGA sample is improved by this study, because we reduced the sample of isolated galaxies used in previous AMIGA works by about 20%. The availability of the spectroscopic data allows us to check the validity of the CIG isolation criteria, which is not fully efficient. About 50% of the neighbours considered as potential companions in the photometric study are in fact background objects. We also find that about 92% of the neighbour galaxies that show recession velocities similar to the corresponding CIG galaxy are not considered by the CIG isolation criteria as potential companions, which may have a considerable influence on the evolution of the central CIG galaxy.
