- ID:
- ivo://CDS.VizieR/J/ApJ/895/78
- Title:
- [Fe/H] and [{alpha}/Fe] in M31 dwarf galaxies
- Short Name:
- J/ApJ/895/78
- Date:
- 15 Mar 2022 06:34:41
- Publisher:
- CDS
- Description:
- We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution (R~6000) spectra obtained with the KeckII telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We coadd stars according to their similarity in photometric metallicity or effective temperature to obtain a signal-to-noise ratio (S/N) high enough to measure average [Fe/H] and [{alpha}/Fe] abundances. We validate our method using high S/N spectra of RGB stars in Milky Way globular clusters, as well as deep observations for a subset of the M31 dSphs in our sample. For this set of validation coadds, we compare the weighted average abundance of the individual stars with the abundance determined from the coadd. We present individual and coadded measurements of [Fe/H] and [{alpha}/Fe] for stars in 10 M31 dSphs, including the first [{alpha}/Fe] measurements for And IX, XIV, XV, and XVIII. These fainter, less massive dSphs show declining [{alpha}/Fe] relative to [Fe/H], implying an extended star formation history (SFH). In addition, these dSphs also follow the same mass-metallicity relation found in other Local Group satellites. The conclusions we infer from coadded spectra agree with those from previous measurements in brighter M31 dSphs with individual abundance measurements, as well as conclusions from photometric studies. These abundances greatly increase the number of spectroscopic measurements of the chemical composition of M31's less massive dwarf satellites, which are crucial to understanding their SFH and interaction with the M31 system.
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- 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/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/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/other/ApSS/364.172
- Title:
- 504 F-G dwarfs photometric metallicities
- Short Name:
- J/other/ApSS/364
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study, photometric metallicity and absolute magnitude calibrations were derived using F-G spectral type main-sequence stars in the Solar neighbourhood with precise spectroscopic, photometric and Gaia astrometric data for UBV photometry. The sample consists of 504 main-sequence stars covering the temperature, surface gravity and colour index intervals 5300<Teff<7300K, logg>4 (cgs) and 0.3<(B-V)0<0.8mag, respectively. Stars with relative trigonometric parallax errors {sigma}_{pi}/{pi}<=0.01 were preferred from Gaia DR2 data for the estimation of their M_V absolute magnitudes. In order to obtain calibrations, (U-B)0 and (B-V)0 colour indices of stars were preferred and a multi-variable second order equation was used. Calibrations are valid for main-sequence stars in the metallicity and absolute magnitude ranges -2<[Fe/H]<0.5dex and 2.5<M_V_<6mag, respectively. The mean value and standard deviation of the differences between original and estimated values for the metal abundance and absolute magnitude are <{Delta}[Fe/H]>=0.00+/-0.11dex and <{Delta}M_V_>=0.00+/-0.22mag, respectively. In this work, it has been shown that more precise iron abundance and absolute magnitude values were obtained with the new calibrations, compared to previous calibrations in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/9
- Title:
- FGK stars magnetic activity in LAMOST-Kepler field
- Short Name:
- J/ApJS/247/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Monitoring chromospheric and photospheric indexes of magnetic activity can provide valuable information, especially the interaction between different parts of the atmosphere and their response to magnetic fields. We extract chromospheric indexes, S and R_HK_^+^, for 59816 stars from LAMOST spectra in the LAMOST-Kepler program, and photospheric index, Reff, for 5575 stars from Kepler light curves. The log Reff shows positive correlation with logR_HK_^+^. We estimate the power-law indexes between Reff and R_HK_^+^ for F-, G-, and K-type stars, respectively. We also confirm the dependence of both chromospheric and photospheric activity on stellar rotation. Ca ii H and K emissions and photospheric variations generally decrease with increasing rotation periods for stars with rotation periods exceeding a few days. The power-law indexes in exponential decay regimes show different characteristics in the two activity-rotation relations. The updated largest sample including the activity proxies and reported rotation periods provides more information to understand the magnetic activity for cool stars.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A12
- Title:
- Foreground Galactic stars properties
- Short Name:
- J/A+A/555/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the chemical and kinematic properties of roughly a thousand FLAMES-GIRAFFE LR8 spectra of faint magnitude foreground Galactic stars observed serendipitously during extra-galactic surveys in four lines-of-sight: three in the southern Galactic hemisphere (surveys of the Carina, Fornax and Sculptor dwarf spheroidal galaxies) and one in the northern Galactic hemisphere (a survey of the Sextans dwarf spheroidal galaxy). The foreground stars span distances up to ~3kpc from the Galactic plane and Galactocentric radii up to 11kpc. The stellar atmospheric parameters (effective temperature, surface gravity, metallicity) are obtained by an automated parameterisation pipeline and the distances of the stars are then derived by a projection of the atmospheric parameters on a set of theoretical isochrones using a Bayesian approach. The metallicity gradients are estimated for each line-of-sight and compared with predictions from the Besancon model of the Galaxy, in order to test the chemical structure of the thick disc. Finally, we use the radial velocities in each line-of-sight to derive a proxy for either the azimuthal or the vertical component of the orbital velocity of the stars. Only three lines-of-sight have a sufficient number of foreground stars for a robust analysis. Towards Sextans in the Northern Galactic hemisphere and Sculptor in the South, we measure a consistent decrease in mean metallicity with height from the Galactic plane, suggesting a chemically symmetric thick disc. This decrease can either be due to an intrinsic thick disc metallicity gradient, or simply due to a change in the thin disc/thick disc population ratio and no intrinsic metallicity gradients for the thick disc. We favour the latter explanation. In contrast, we find evidence of an unpredicted metal-poor population in the direction of Carina. This population was earlier detected by Wyse et al. (2006ApJ...639L..13W), but our more detailed analysis provides robust estimates of its location (|Z|<1kpc), metallicity (-2<[M/H]<-1dex) and azimuthal orbital velocity (V_phi_~120km/s).
- ID:
- ivo://CDS.VizieR/J/A+A/637/A26
- Title:
- Fornax 3D project. Globular clusters
- Short Name:
- J/A+A/637/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters (GCs) are found ubiquitously in massive galaxies and due to their old ages, they are regarded as fossil records of galaxy evolution. Spectroscopic studies of GC systems are often limited to the outskirts of galaxies, where GCs stand out against the galaxy background and serve as bright tracers of galaxy assembly. In this work we use the capabilities of the Multi Unit Explorer Spectrograph (MUSE) to extract a spectroscopic sample of 722 GCs in the inner regions (<3Reff) of 32 galaxies in the Fornax cluster. These galaxies were observed as part of the Fornax 3D project, a MUSE survey that targets early and late-type galaxies within the virial radius of Fornax. After accounting for the galaxy background in the GC spectra, we extracted line-of-sight velocities and determined metallicities of a subsample of 238 GCs. We found signatures of rotation within GC systems and comparing the GC kinematics and that of the stellar body shows that the angular momentum of the GC system reflects that of the stars, confirming the usefulness of GCs as kinematic tracers. While the red GCs prove to closely follow the metallicity profile of the host galaxy, the blue GCs show a large spread of metallicities but are generally more metal -poor than the host.
