- ID:
- ivo://CDS.VizieR/J/A+A/404/661
- Title:
- Fe5270, Fe5335, Mgb and Mg_2_ synthetic indices
- Short Name:
- J/A+A/404/661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have computed a grid of synthetic spectra in the wavelength range {lambda}{lambda}4600-5600{AA} using revised model atmospheres, for a range of atmospheric parameters and values of [alpha-elements/Fe]=0.0 and +0.4. The Lick indices Fe5270, Fe5335, Mgb and Mg_2_ are measured on the grid spectra, for FWHM=2 to 8.3{AA}. Relations between the indices Fe5270, Fe5335 and Mg_2_ and stellar parameters effective temperature T_eff_, logg, [Fe/H] and [alpha/Fe], valid in the range 4000K>=T_eff_>=7000K, are presented. These fitting functions are given for FWHM=3.5 and 8.3{AA}. The indices were also measured for a list of 97 reference stars with well-known stellar parameters observed at ESO and OHP, and these are compared to the computed indices. Finally, a comparison of the indices measured on the observed spectra and those derived from the fitting functions based on synthetic spectra is presented.
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- ID:
- ivo://CDS.VizieR/J/A+A/599/A12
- Title:
- [Fe/H] and kinematics of 26 Galactic bulge fields
- Short Name:
- J/A+A/599/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several recent studies have demonstrated that the Galactic bulge hosts two components with different mean metallicities, and possibly different spatial distribution and kinematics. As a consequence, both the metallicity distribution and the radial velocity of bulge stars vary across different line of sights. We present here the metallicity distribution function of red clump stars in 26 fields spread across a wide area of the bulge, with special emphasis on fields close to Galactic plane, at latitudes b=-2 and b=-1, that were not explored before. This work includes new metallicities from a sample of ~5000 K giant stars, observed at spectral resolution R~6500, in the Calcium II Triplet region. They are the main dataset of the GIRAFFE Inner Bulge Survey. As part of the same survey we have previously published results for a sample of ~600 K giant stars, at latitude b~-4 derived from higher resolution spectra (R=22500). The combined sample allows us to trace and characterize the metal poor and metal rich bulge populations down to the inner bulge. We present a density map for each of the two components. Contrary to the expectations from previous works, we found the metal poor population to be more centrally concentrated than the metal rich one, and with a more axisymmetric spatial distribution. The metal rich population, on the other hand, is arranged in a boxy distribution, consistent with an edge-on bar. By coupling metallicities and radial velocities we show that the metal poor population has a velocity dispersion that varies rather mildly with latitude. On the contrary, the metal rich population has a low velocity dispersion far from the plane (b=-8.5) but it has a steeper gradient with latitude, becoming higher than the metal poor one in the innermost field (b=-1). This work provides new observational constraints on the actual chemodynamical properties of the Galactic bulge, that will help discriminating among different formation models.
- ID:
- ivo://CDS.VizieR/J/ApJS/161/444
- Title:
- [Fe/H] and Teff for luminosity class IV-V stars
- Short Name:
- J/ApJS/161/444
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, an updated catalog containing averaged values of [Fe/H] is presented for FGK stars on and near the main sequence. The input data for the catalog are values of [Fe/H] derived from weak and moderately strong lines and published before 2005 July 1. Those data are corrected to a uniform temperature scale, and a statistical analysis is then applied to a subset of the data that did not contribute to a previous version of the catalog. In this way, it is found that an accurate zero point for the catalog can be established with an rms error of 0.005dex. After corrections are applied to a number of the newly added data, it is shown that those corrections help to produce satisfactory zero-point coherence among the catalog entries. Standard errors that are derived for the catalog data are shown to be accurate. It is also shown that those standard errors are based on pervasive scatter in the input data, as is expected if those data are affected by genuine random effects. Samples of the metallicity catalog and an accompanying temperature catalog are displayed and discussed. To make possible an effective extension of the catalog to stars without catalog entries, a database containing photometric metallicities derived by Nordstroem et al. (2004, Cat. <V/117>) is considered. Standard errors for those metallicities are derived, and zero-point corrections required to put those data on the catalog zero point are presented.
- ID:
- ivo://CDS.VizieR/J/A+A/398/731
- Title:
- [Fe/H] catalog of class IV-V stars
- Short Name:
- J/A+A/398/731
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains mean values of [Fe/H] (with rms errors) for 941 F-K stars which are on or near the main sequence. Literature references are given for the contributing values of [Fe/H]
- ID:
- ivo://CDS.VizieR/J/ApJ/833/225
- Title:
- -2.6<=[Fe/H]<=0.2 F and G dwarfs. II. Abundances
- Short Name:
- J/ApJ/833/225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the first time, we present an extensive study of stars with individual non-LTE (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over the -2.62<=[Fe/H]<=+0.24 metallicity range that is suitable for the Galactic chemical evolution research. The star sample has been kinematically selected to trace the Galactic thin and thick disks and halo. We find new results and improve earlier ones as follows: (i) the element-to-iron ratios for Mg, Si, Ca, and Ti form a metal-poor (MP) plateau at a similar height of 0.3 dex, and the knee occurs at common [Fe/H]~-0.8. The knee at the same metallicity is observed for [O/Fe], and the MP plateau is formed at [O/Fe]=0.61. (ii) The upward trend of [C/O] with decreasing metallicity exists at [Fe/H]<-1.2, supporting the earlier finding of Akerman et al. (iii) An underabundance of Na relative to Mg in the [Fe/H]<-1 stars is nearly constant, with the mean [Na/Mg]~-0.5. (iv) The K/Sc, Ca/Sc, and Ti/Sc ratios form well-defined trends, suggesting a common site of the K-Ti production. (v) Sr follows the Fe abundance down to [Fe/H]~-2.5, while Zr is enhanced in MP stars. (vi) The comparisons of our results with some widely used Galactic evolution models are given. The use of the NLTE element abundances gives increased credit to the interpretation of the data in the context of the chemical evolution of the Galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/415/1153
- Title:
- [Fe/H] for 98 extra-solar planet-host stars
- Short Name:
- J/A+A/415/1153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar parameters and metallicities, obtained from a detailed spectroscopic analysis, for a large sample of 98 stars known to be orbited by planetary mass companions (almost all known targets), as well as for a volume-limited sample of 41 stars not known to host any planet. For most of the stars the stellar parameters are revised versions of the ones presented in our previous work. However, we also present parameters for 18 stars with planets not previously published, and a compilation of stellar parameters for the remaining 4 planet-hosts for which we could not obtain a spectrum. A comparison of our stellar parameters with values of Teff, logg, and [Fe/H] available in the literature shows a remarkable agreement. In particular, our spectroscopic logg values are now very close to trigonometric logg estimates based on Hipparcos parallaxes. The derived [Fe/H] values are then used to confirm the previously known result that planets are more prevalent around metal-rich stars.
- ID:
- ivo://CDS.VizieR/J/A+A/312/111
- Title:
- [Fe/H] from RR Lyrae light curves
- Short Name:
- J/A+A/312/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an accurate and robust method for the calculation of [Fe/H] from the light curves of RRab stars. The method introduces a considerable improvement relative to our previously published formulae. First of all, it uses an improved and extended data base for the light curves and more accurate, very recent iron abundances. Secondly, the new data base makes it possible to show that the basic relation between [Fe/H] and the Fourier parameters is linear and contains only the period and one of the Fourier phases, most importantly {phi}_31_. Last but not least, we derive interrelations among the Fourier parameters which help us to filter out peculiar stars where more caution is needed in accepting the calculated abundance. The applicability of the method is demonstrated on independent samples of globular cluster stars. Peculiarities encountered in Blazhko variables and in some other cases are also discussed. The Fourier decomposition is defined by the formula: V(t) = A0 + A1*sin(2*pi/P*(t-t0)+phi1) + A2*sin(2*pi*2/P*(t-t0)+phi2) +... + A15*sin(2*pi*15/P*(t-t0)+phi15) V(t) -- light curve in Johnson V P -- period t0 -- Epoch = 2400000.0
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/2418
- Title:
- [Fe/H] of short-period Galactic Cepheids
- Short Name:
- J/MNRAS/434/2418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the study of the metallicity dependence of the Fourier amplitude ratios R_21_ and R_31_ for the light curves of short-period Galactic classical Cepheids in B, V, R_C_ and I_C_ bands. Based on the available photometric and spectroscopic data, we determined the relations between the atmospheric iron abundance, [Fe/H], and the Fourier parameters. Using these relations we calculated the photometric [Fe/H] values of all programme Cepheids with an average accuracy of +/-0.15dex. No spectroscopic iron abundance was known before for 14 of these stars. These empirical results provide an alternate method to determine the iron abundance of classical Cepheids too faint for spectroscopic observations. We also checked whether the metal-poor Cepheids of both Magellanic Clouds follow the same relationships, and a good agreement was found.
- ID:
- ivo://CDS.VizieR/V/58
- Title:
- [Fe/H], Vel, Orbits of F2-K5 Dwarfs 80pc from Sun
- Short Name:
- V/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this catalog, metallicities, distances, components of space velocities and parameters of osculating orbits are calculated for 1065 F2-K5 dwarfs with UBV photometric data, proper motions and radial velocities. The present sample is composed on the base of the Ochsenbein (1980) catalogue and contains the stars of the V (IV-V) luminosity class, within the colour range 0.35<B-V<1.10 (which corresponds to the spectral class range F2-K5). Sandage's (1969) Hyades sequence was used to determine the value delta (U-B) for each star. The authors calibrated the ultraviolet excess in terms of [Fe/H] separately for the four of the temperature index (B-V) where delta(U-B) practically does not depend on the effective temperature. Intervals in (B-V) correspond to the following division on spectral class intervals: F2-F9, G0-G4, and G5-G9, K0-K5. Metallicity is calculated from the formulae: [Fe/H]=-5.3*delta(U-B)+0.02 for stars F2-F9 [Fe/H]=-5.1*delta(U-B)+0.13 for stars G0-G4 [Fe/H]=-5.4*delta(U-B)+0.02 for stars G5-G9 [Fe/H]=-4.7*delta(U-B)-0.04 for stars K0-K5 These relations follow from the assumption that mean metallicity and metallicity dispersion for stars of all spectral classes are the same. Distances to the stars were calculated from spectral parallaxes. Absolute magnitudes (M(V)) were obtained from the Sp,M(V)-relation for dwarfs (Straizys, 1982). The sample includes only stars nearer than 80 pc because reddening is negligible for them. The obtained distances together with radial velocities and proper motions are used to calculate the components of space velocities. The eccentricities, apogalactic and perigalactic distances of the stars were calculated from the osculating orbit approximation according to the galaxy model from the paper by Eggen et al. (1962).
- ID:
- ivo://CDS.VizieR/J/A+A/628/A54
- Title:
- Fe, Mg, Ti in Galactic clusters
- Short Name:
- J/A+A/628/A54
- Date:
- 02 Nov 2021 11:16:10
- Publisher:
- CDS
- Description:
- We test the effects of non-local thermodynamic equilibrium (NLTE) on the spectra of FGK-type stars across a wide range of metallicity and to derive abundance of Fe, Mg, and Ti for a sample of Galactic star clusters. We extend the Payne fitting approach to draw on NLTE and LTE spectral models in order to determine stellar parameters and chemical abundances for the Gaia-ESO benchmark stars. We also analyse the medium-resolution Giraffe spectra of 742 stars in 13 open and globular clusters in the Milky Way galaxy. We show that this approach accurately recovers effective temperatures, surface gravities, and abundances of the benchmark stars and clusters members. The differences between NLTE and LTE stellar parameters are small for the metal-rich stars. However, for metal-poor stars [Fe/H]<-1, the NLTE estimates of Teff, log(g) and [Fe/H] are higher than LTE estimates, and the systematic offset increases with decreasing metallicity. Our LTE measurements of metallicities and abundances in the Galactic clusters are in a good agreement with the earlier literature studies. For the majority of these clusters, our study yields the first estimates of NLTE abundances of Fe, Mg and Ti. The NLTE [Fe/H] are systematically higher, whereas the average NLTE [Mg/Fe] abundance ratios are ~0.15dex lower, compared to LTE. All clusters investigated in this work appear homogeneous in Fe and Ti, with the intra-cluster abundance variations of less then 0.1dex. We confirm large dispersions of [Mg/Fe] ratios for NGC 2808, NGC 4833 and M 15. Our results shows that NLTE analysis change the mean abundance ratios in the clusters, but does not influence the intra-cluster abundance dispersions. Combining the Payne fitting approach with NLTE spectral models as input is a powerful tool for a detailed exploration of the large-scale spectroscopic stellar surveys.
