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1581. Metal abundances of KISS galaxies. V.
ID:
ivo://CDS.VizieR/J/AJ/150/71
Title:
Metal abundances of KISS galaxies. V.
Short Name:
J/AJ/150/71
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high signal-to-noise ratio spectroscopy of 15 emission-line galaxies cataloged in the KPNO International Spectroscopic Survey, selected for their possession of high equivalent width [OIII] lines. The primary goal of this study was to attempt to derive direct-method (T_e_) abundances for use in constraining the upper-metallicity branch of the R_23_ relation. The spectra cover the full optical region from [OII]{lambda}{lambda}3726,3729 to [SIII]{lambda}{lambda}9069,9531 and include the measurement of [OIII]{lambda}4363 in 13 objects. From these spectra, we determine abundance ratios of helium, nitrogen, oxygen, neon, sulfur, and argon. We find these galaxies to predominantly possess oxygen abundances in the range of 8.0<~12+log(O/H)<~8.3. We present a comparison of direct-method abundances with empirical strong-emission-line techniques, revealing several discrepancies. We also present a comparison of direct-method oxygen abundance calculations using electron temperatures determined from emission lines of O^++^ and S^++^, finding a small systematic shift to lower T_e_(~1184K) and higher metallicity (~0.14dex) for sulfur-derived T_e_ compared to oxygen-derived T_e_. Finally, we explore in some detail the different spectral activity types of targets in our sample, including regular star-forming galaxies, those with suspected AGN contamination, and a local pair of low-metallicity, high-luminosity compact objects.
1582. METAL Hubble program. I. Initial results
ID:
ivo://CDS.VizieR/J/ApJ/871/151
Title:
METAL Hubble program. I. Initial results
Short Name:
J/ApJ/871/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud (METAL) is a large cycle 24 program on the Hubble Space Telescope aimed at measuring dust extinction properties and interstellar depletions in the Large Magellanic Cloud (LMC) at half-solar metallicity. The 101-orbit program is composed of Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS) spectroscopy toward 33 LMC massive stars between 1150 and 3180{AA} and parallel Wide Field Camera 3 (WFC3) imaging in seven near-UV to near-IR filters. The fraction of silicon in the gas phase (depletion) obtained from the spectroscopy decreases with increasing hydrogen column density. Depletion patterns for silicon differ between the Milky Way, LMC, and Small Magellanic Cloud (SMC), with the silicon depletion level offsetting almost exactly the metallicity differences, leading to constant gas-phase abundances in those galaxies for a given hydrogen column density. The silicon depletion correlates linearly with the absolute-to-selective extinction, RV, indicating a link between gas depletion and dust grain size. Extinction maps are derived from the resolved stellar photometry in the parallel imaging, which can be compared to far-IR images from Herschel and Spitzer to estimate the emissivity of dust at LMC metallicity. The full METAL sample of depletions, UV extinction curves, and extinction maps will inform the abundance, size, composition, and optical properties of dust grains in the LMC, comprehensively improve our understanding of dust properties, and improve the accuracy with which dust-based gas masses, star formation rates, and star formation histories in nearby and high-redshift galaxies are estimated. This overview paper describes the goals, design, data reduction, and initial results of the METAL survey.
1583. Metallicities & activities of southern stars
ID:
ivo://CDS.VizieR/J/A+A/485/571
Title:
Metallicities & activities of southern stars
Short Name:
J/A+A/485/571
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from high-resolution spectroscopic measurements to determine metallicities and activities of bright stars in the southern hemisphere.
1584. Metallicities and abundances of evolved stars
ID:
ivo://CDS.VizieR/J/A+A/588/A98
Title:
Metallicities and abundances of evolved stars
Short Name:
J/A+A/588/A98
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detailed chemical abundance studies have revealed different trends between samples of planet and non-planet hosts. Whether these trends are related to the presence of planets or not is strongly debated. At the same time, tentative evidence that the properties of evolved stars with planets may be different from what we know for main-sequence hosts has been recently reported. We aim to test whether evolved stars with planets show any chemical peculiarity that could be related to the planet formation process. We determine in a consistent way the metallicity and individual abundances of a large sample of evolved (subgiants and red giants) and main-sequence stars with and without known planetary companions, and discuss their metallicity distribution and trends. Our methodology is based on the analysis of high-resolution echelle spectra (R ~ 57000) from 2-3 m class telescopes. It includes the calculation of the fundamental stellar parameters, as well as, individual abundances.
1585. Metallicities of RGB stars in dwarf galaxies
ID:
ivo://CDS.VizieR/J/ApJ/779/102
Title:
Metallicities of RGB stars in dwarf galaxies
Short Name:
J/ApJ/779/102
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z_{star}_{propto}M_{star}_^0.30+/-0.02^. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M_*_=10^12^M_{sun}_. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping.
1586. Metallicities of Slowly Pulsating B stars
ID:
ivo://CDS.VizieR/J/A+A/404/689
Title:
Metallicities of Slowly Pulsating B stars
Short Name:
J/A+A/404/689
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derived the stellar parameters (angular diameters, effective temperatures, metallicities) and interstellar reddenings for 20 Slowly Pulsating B (SPB) and 34 reference stars observed during the IUE satellite mission. The parameters were derived by means of an algorithmic procedure of fitting theoretical flux distributions to the low-resolution IUE spectra and optical spectrophotometric observations. Since the metallicity [m/H] has a special importance for pulsating B type stars, we focused our attention on that parameter. We found that the mean value of the metallicity of the considered SPB and reference stars amounts to [m/H]~-0.20. The results only slightly depend on the reduction procedure used for the IUE images (NEWSIPS and INES). The metal abundances obtained in this paper are in accordance with the average value of -0.2dex for stars in the solar neighborhood recently reported by other investigators.
1587. Metallicity evolution of COSMOS BCD sample
ID:
ivo://CDS.VizieR/J/ApJ/819/73
Title:
Metallicity evolution of COSMOS BCD sample
Short Name:
J/ApJ/819/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and D_n_(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass-metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D_n_(4000) index values. The insignificant deviation in the mass-metallicity and mass-SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.
1588. Metallicity of MPA-JHU SDSS-DR7 dwarf galaxies
ID:
ivo://CDS.VizieR/J/ApJ/834/186
Title:
Metallicity of MPA-JHU SDSS-DR7 dwarf galaxies
Short Name:
J/ApJ/834/186
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study how the cosmic environment affects galaxy evolution in the universe by comparing the metallicities of dwarf galaxies in voids with dwarf galaxies in more dense regions. Ratios of the fluxes of emission lines, particularly those of the forbidden [OIII] and [SII] transitions, provide estimates of a region's electron temperature and number density. From these two quantities and the emission line fluxes [OII]{lambda}3727, [OIII]{lambda}4363, and [OIII]{lambda}{lambda}4959,5007, we estimate the abundance of oxygen with the direct T_e_ method. We estimate the metallicity of 42 blue, star-forming void dwarf galaxies and 89 blue, star-forming dwarf galaxies in more dense regions using spectroscopic observations from the Sloan Digital Sky Survey Data Release 7, as reprocessed in the MPA-JHU value-added catalog. We find very little difference between the two sets of galaxies, indicating little influence from the large-scale environment on their chemical evolution. Of particular interest are a number of extremely metal-poor dwarf galaxies that are less prevalent in voids than in the denser regions.
1589. Metallicity of solar-type stars
ID:
ivo://CDS.VizieR/J/A+A/541/A40
Title:
Metallicity of solar-type stars
Short Name:
J/A+A/541/A40
Date:
21 Oct 2021
Publisher:
CDS
Description:
Around 16% of the solar-like stars in our neighbourhood show IR-excesses due to dusty debris discs and a fraction of them are known to host planets. Determining whether these stars follow any special trend in their properties is important to understand debris disc and planet formation. We aim to determine in a homogeneous way the metallicity of a sample of stars with known debris discs and planets. We attempt to identify trends related to debris discs and planets around solar-type stars Our analysis includes the calculation of the fundamental stellar parameters Teff, logg, microturbulent velocity, and metallicity by applying the iron ionisation equilibrium conditions to several isolated FeI and FeII lines. High-resolution echelle spectra (R~57000) from 2, 3m class telescopes are used. Our derived metallicities are compared with other results in the literature, which finally allows us to extend the stellar samples in a consistent way.
1590. Metallicity of the {gamma} Vel cluster
ID:
ivo://CDS.VizieR/J/A+A/567/A55
Title:
Metallicity of the {gamma} Vel cluster
Short Name:
J/A+A/567/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Knowledge of the abundance distribution of star forming regions and young clusters is critical to investigate a variety of issues, from triggered star formation and chemical enrichment by nearby supernova explosions to the ability to form planetary systems. In spite of this, detailed abundance studies are currently available for relatively few regions. In this context, we present the analysis of the metallicity of the Gamma Velorum cluster, based on the products distributed in the first internal release of the Gaia-ESO Survey. The Gamma Velorum candidate members have been observed with FLAMES, using both UVES and Giraffe, depending on the target brightness and spectral type. In order to derive a solid metallicity determination for the cluster, membership of the observed stars must be first assessed. To this aim, we use several membership criteria including radial velocities, surface gravity estimates, and the detection of the photospheric lithium line. Out of the 80 targets observed with UVES, we identify 14 high-probability members. We find that the metallicity of the cluster is slightly sub-solar, with a mean [Fe/H]=-0.057+/-0.018dex. Although J08095427-4721419 is one of the high-probability members, its metallicity is significantly larger than the cluster average. We speculate about its origin as the result of recent accretion episodes of rocky bodies of about 60 Msun hydrogen-depleted material from the circumstellar disc.

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