- ID:
- ivo://CDS.VizieR/J/A+A/563/A15
- Title:
- Metallicity and kinematics in Galactic bar
- Short Name:
- J/A+A/563/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observe red clump stars in four fields along the Galactic bar major axis (l=10{deg}, -6{deg}, 6{deg} and b=0{deg}, plus a field at l=0{deg}, b=1{deg}) with low-resolution spectroscopy from FLAMES/GIRAFFE (setup LR08) at the VLT, observing around the CaII triplet. We developed robust methods to extract radial velocity and metallicity estimates from these low signal-to-noise spectra. Results have been derived by fixing atmospheric parameters typical of a red clump star (Teff=4750K, logg=2.5). For some targets, the metallicity could not be derived.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1793
- Title:
- Metallicity calibrations for UBV photometry
- Short Name:
- J/MNRAS/371/1793
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Calibrations are presented here for metallicity ([Fe/H]) in terms of the ultraviolet excess, [{Delta}(U-B) at B-V=0.6, hereafter D0.6], and also for the absolute visual magnitude (M_V_) and its difference with respect to the Hyades ({Delta}M^H^_V_) in terms of D0.6 and (B-V), making use of high-resolution spectroscopic abundances from the literature and Hipparcos parallaxes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/194
- Title:
- Metallicity distribution in the GC
- Short Name:
- J/MNRAS/464/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowing the metallicity distribution of stars in the Galactic Centre has important implications for the formation history of the Milky Way nuclear star cluster. However, this distribution is not well known, and is currently based on a small sample of fewer than 100 stars. We obtained near-infrared K-band spectra of more than 700 late-type stars in the central 4pc^2^ of the Milky Way nuclear star cluster with the integral-field spectrograph KMOS (VLT). We analyse the medium-resolution spectra using a full-spectral fitting method employing the Gottingen spectral library of synthetic PHOENIX spectra. The derived stellar metallicities range from metal-rich [M/H]>+0.3dex to metal-poor [M/H]<-1.0dex, with a fraction of 5.2^+6.0^_-3.1_ per cent metal-poor ([M/H]<=-0.5dex) stars. The metal-poor stars are distributed over the entire observed field. The origin of metal-poor stars remains unclear. They could originate from infalling globular clusters. For the metal-rich stellar population ([M/H]>0dex), a globular cluster origin can be ruled out. As there is only a very low fraction of metal-poor stars in the central 4pc^2^ of the Galactic Centre, we believe that our data can discard a scenario in which the Milky Way nuclear star cluster is purely formed from infalling globular clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/508/1285
- Title:
- Metallicity estimates of M31 globular clusters
- Short Name:
- J/A+A/508/1285
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new homogeneous set of metallicity estimates based on Lick indices for the old globular clusters of the M31 galaxy. The final aim is to add homogeneous spectroscopic metallicities to as many entries as possible of the Revised Bologna Catalog of M31 (www.bo.astro.it/M31) clusters, by reporting Lick index measurements from any source (literature, new observations, etc.) on the same scale.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/587/L7
- Title:
- Metallicity from Type II SN from (i)PTF
- Short Name:
- J/A+A/587/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type IIP supernovae (SNe IIP) have recently been proposed as metallicity (Z) probes. The spectral models of Dessart et al. (2014MNRAS.440.1856D) showed that the pseudo-equivalent width of FeII {lambda}5018 (pEW_5018_) during the plateau phase depends on the primordial Z, but there was a paucity of SNe IIP exhibiting pEW_5018_ that were compatible with Z<0.4Z_{sun}_. This lack might be due to some physical property of the SN II population or to the fact that those SNe have been discovered in luminous, metal-rich targeted galaxies. Here we use SN II observations from the untargeted (intermediate) Palomar Transient Factory [(i)PTF] survey, aiming to investigate the pEW_5018_ distribution of this SN population and, in particular, to look for the presence of SNe II at lower Z. We perform pEW_5018_ measurements on the spectra of a sample of 39 (i)PTF SNe II, selected to have well-constrained explosion epochs and light-curve properties. Based on the comparison with the pEW_5018_ spectral models, we subgrouped our SNe into four Z bins from Z=~0.1 Z_{sun}_ up to Z=~2 Z_{sun}_. We also independently investigated the Z of the hosts by using their absolute magnitudes and colors and, in a few cases, using strong-line diagnostics from spectra. We searched for possible correlations between SN observables, such as their peak magnitudes and the Z inferred from pEW_5018_. We found 11 events with pEW_5018_ that were small enough to indicate Z=~0.1 Z_{sun}_. The trend of pEW_5018_ with Z matches the Z estimates obtained from the host-galaxy photometry, although the significance of the correlation is weak. We also found that SNe with brighter peak magnitudes have smaller pEW_5018_ and occur at lower Z.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A112
- Title:
- Metallicity-giant planet correlation
- Short Name:
- J/A+A/551/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is generally accepted that the presence of a giant planet is strongly dependent on the stellar metallicity. A stellar mass dependence has also been investigated, but this dependence does not seem as strong as the metallicity dependence. Even for metallicity however, the exact form of the correlation has not been established. In this paper, we test several scenarios to describe the frequency of giant planets as a function of its host parameters. We perform this test on two volume-limited samples (from CORALIE and HARPS). By using a Bayesian analysis, we can quantitatively compare the different scenarios. We confirm that giant planet frequency is indeed a function of metallicity. However, there is no statistical difference between a constant or an exponential function for stars with subsolar metallicities contrarily to what has been previously stated in the literature. The dependence on stellar mass could not be confirmed, neither discarded.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1916
- Title:
- Metallicity indices in open clusters
- Short Name:
- J/AJ/130/1916
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present metallicity estimates for seven open clusters based on spectrophotometric indices from moderate-resolution spectroscopy. Observations of field giants of known metallicity provide a correlation between the spectroscopic indices and the metallicity of open cluster giants. We use 2 analysis to fit the relation of spectrophotometric indices to metallicity in field giants. The resulting function allows an estimate of the target-cluster giants' metallicities with an error in the method of +/-0.08 dex. We derive the following metallicities for the seven open clusters: NGC 1245, [M/H]=-0.14+/-0.04; NGC 2099, [M/H]=+0.05+/-0.05; NGC 2324, [M/H]=-0.06+/-0.04; NGC 2539, [M/H]=-0.04+/-0.03; NGC 2682 (M67), [M/H]=-0.05+/-0.02; NGC 6705, [M/H]=+0.14+/-0.08; NGC 6819, [M/H]=-0.07+/-0.12. These metallicity estimates will be useful in planning future extrasolar planet transit searches, since planets may form more readily in metal-rich environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/110
- Title:
- Metallicity measurements in 70 nearby galaxies
- Short Name:
- J/ApJ/862/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the metallicity dependence of HI surface densities in star-forming regions along many lines of sight within 70 nearby galaxies, probing kiloparsec to 50pc scales. We employ HI, SFR, stellar mass, and metallicity (gradient) measurements from the literature, spanning a wide range (5dex) in stellar and gas mass and (1.6dex) in metallicity. We consider metallicities as observed, or rescaled to match the mass-metallicity relation determined for SDSS galaxies. At intermediate to high metallicities (0.3-2 times solar), we find that the HI surface densities saturate at sufficiently large total gas surface density. The maximal HI columns vary approximately inversely with metallicity, and show little variation with spatial resolution, galactocentric radius, or among galaxies. In the central parts of massive spiral galaxies, the HI gas is depressed by factors of ~2. The observed behavior is naturally reproduced by metallicity dependent shielding theories for the HI-to-H2 transitions in star-forming galaxies. We show that the inverse scaling of the maximal HI columns with metallicity suggests that the area filling fraction of atomic-molecular complexes in galaxies is of the order of unity, and weakly dependent on metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A80
- Title:
- Metallicity of bulge clump giants in Baade's window
- Short Name:
- J/A+A/534/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We seek to constrain the formation of the Galactic bulge by means of analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. These stars were selected to minimise the contamination by other Galactic components, so they are good tracers of the bulge metallicity distribution in Baade's window, at least for stars more metal-rich than ~-1.5. We used an automatic procedure to measure [Fe/H] in a sample of 219 bulge red clump stars from R=20000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT. The analysis was performed differentially with respect to the metal-rich local reference star MuLeo. For a subsample of 162 stars, we also derived [Mg/H] from spectral synthesis around the MgI triplet at 6319{AA}. The Fe and Mg metallicity distributions are both asymmetric with median values of +0.16 and +0.21, respectively. They show only a small proportion of stars at low metallicities, extending down to [Fe/H]=-1.1 or [Mg/H]=-0.7 The iron distribution is clearly bimodal, as revealed both by a deconvolution (from observational errors) and a Gaussian decomposition. The decomposition of the observed Fe and Mg metallicity distributions into Gaussian components yields two populations of equal sizes (50% each): a metal-poor component centred on [Fe/H]=-0.30 and [Mg/H]=-0.06 with a large dispersion and a narrow metal-rich component centred on [Fe/H]=+0.32 and [Mg/H]=+0.35. The metal-poor component shows high [Mg/Fe] ratios (around 0.3), while stars in the metal-rich component are found to have near solar ratios. Kinematical differences between the two components have also been found: the metal-poor component shows kinematics compatible with an old spheroid, while the metal-rich component is consistent with a population supporting a bar. In view of their chemical and kinematical properties, we suggest different formation scenarii for the two populations: a rapid formation time scale as an old spheroid for the metal-poor component (old bulge) and for the metal-rich component, a formation on a longer time scale driven by the evolution of the bar (pseudo-bulge).
