- ID:
- ivo://CDS.VizieR/J/A+A/573/A55
- Title:
- Gaia-ESO Survey: Tr 20, NGC4815, NGC6705
- Short Name:
- J/A+A/573/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Public Spectroscopic Survey will observe a large sample of clusters and cluster stars, covering a wide age-distance-metallicity-position-density parameter space. We aim to determine C, N, and O abundances in stars of Galactic open clusters of the Gaia-ESO survey and to compare the observed abundances with those predicted by current stellar and Galactic evolution models. In this pilot paper, we investigate the first three intermediate-age open clusters. High-resolution spectra, observed with the FLAMES-UVES spectrograph on the ESO VLT, were analysed using a differential model atmosphere method. Abundances of carbon were derived using the C_2_ band heads at 5135 and 5635.5{AA}. The wavelength interval 6470-6490{AA}, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [OI] line at 6300{AA}. The mean values of the elemental abundances in Trumpler 20 as determined from 42 stars are: [Fe/H]=0.10+/-0.08 (s.d.), [C/H]=-0.10+/-0.07, [N/H]=0.50+/-0.07, and consequently C/N=0.98+/-0.12. We measure from five giants in NGC 4815: [Fe/H]=-0.01+/-0.04, [C/H]=-0.17+/-0.08, [N/H]=0.53+/-0.07, [O/H]=0.12+/-0.09, and C/N=0.79+/-0.08. We obtain from 27 giants in NGC 6705: [Fe/H]=0.0+/-0.05, [C/H]=-0.08+/-0.06, [N/H]=0.61+/-0.07, [O/H]=0.13+/-0.05, and C/N=0.83+/-0.19. The C/N ratios of stars in the investigated open clusters were compared with the ratios predicted by stellar evolutionary models. For the corresponding stellar turn-off masses from 1.9 to 3.3M_{sun}_, the observed C/N ratio values are very close to the predictions of standard first dredge-up models as well as to models of thermohaline extra-mixing. They are not decreased as much as predicted by the recent model in which the thermohaline- and rotation-induced extra-mixing act together. The average [O/H] abundance ratios of NGC 4815 and NGC 6705 are compared with the predictions of two Galactic chemical evolution models. The data are consistent with the evolution at the solar radius within the errors. The first results of CNO determinations in open clusters show the potential of the Gaia-ESO Survey to judge stellar and Galactic chemical evolution models and the validity of their physical assumptions through a homogeneous and detailed spectral analysis.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/598/A68
- Title:
- Gaia-ESO Survey. Trumpler 23
- Short Name:
- J/A+A/598/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trumpler 23 is a moderately populated, intermediate-age open cluster within the solar circle at a R_GC_~6kpc. It is in a crowded field very close to the Galactic plane and the color-magnitude diagram shows significant field contamination and possible differential reddening; it is a relatively understudied cluster for these reasons, but its location makes it a key object for determining Galactic abundance distributions. New data from the Gaia-ESO Survey enable the first ever radial velocity and spectroscopic metallicity measurements for this cluster. We aim to use velocities to isolate cluster members, providing more leverage for determining cluster parameters. Gaia-ESO Survey data for 167 potential members have yielded radial velocity measurements, which were used to determine the systemic velocity of the cluster and membership of individual stars. Atmospheric parameters were also used as a check on membership when available. Literature photometry was used to re-determine cluster parameters based on radial velocity member stars only; theoretical isochrones are fit in the V, V-I diagram. Cluster abundance measurements of ten radial-velocity member stars with high-resolution spectroscopy are presented for 24 elements. These abundances have been compared to local disk stars, and where possible placed within the context of literature gradient studies. We find Trumpler 23 to have an age of 0.80+/-0.10Gyr, significant differential reddening with an estimated mean cluster E(V-I) of 1.02^+0.14^_-0.09_, and an apparent distance modulus of 14.15+/-0.20. We find an average cluster metallicity of [Fe/H]=0.14+/-0.03dex, a solar [{alpha}/Fe] abundance, and notably subsolar [s-process/Fe] abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A81
- Title:
- Gaia FGK benchmark stars: abundances
- Short Name:
- J/A+A/582/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the current era of large spectroscopic surveys of the Milky Way, reference stars for calibrating astrophysical parameters and chemical abundances are of paramount importance. We determine elemental abundances of Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni for our predefined set of Gaia FGK benchmark stars. By analysing high-resolution spectra with a high signal-to-noise ratio taken from several archive datasets, we combined results of eight different methods to determine abundances on a line-by-line basis. We performed a detailed homogeneous analysis of the systematic uncertainties, such as differential versus absolute abundance analysis. We also assessed errors that are due to non-local thermal equilibrium and the stellar parameters in our final abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A133
- Title:
- Gaia FGK benchmark stars: metallicity
- Short Name:
- J/A+A/564/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or "benchmark stars", with well-defined parameters to be used as a reference. We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities.
- ID:
- ivo://CDS.VizieR/III/281
- Title:
- Gaia FGK benchmark stars v2.1
- Short Name:
- III/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this era of large spectroscopic surveys of stars of the Milky Way, pipelines need to be tested and validated against a set of well-known stars. The Gaia FGK benchmark stars (GBS) are among the preferred samples of reference stars. They consist of a small but carefully selected sample of stars whose parameters are derived consistently and homogeneously. A series of papers has been published that discuss the definition and evolution of the sample of GBS. Here we summarise this work and provide our current list of stars with associated parameters which are recommended for validation and calibration purposes for stellar surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A70
- Title:
- Gaia FGK stars: low-metallicities candidates
- Short Name:
- J/A+A/592/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have entered an era of large spectroscopic surveys in which we can measure, through automated pipelines, the atmospheric parameters and chemical abundances for large numbers of stars. Calibrating these survey pipelines using a set of "benchmark stars" in order to evaluate the accuracy and precision of the provided parameters and abundances is of utmost importance. The recent proposed set of Gaia FGK benchmark stars has up to five metal-poor stars but no recommended stars within -2.0<[Fe/H]<-1.0dex. However, this metallicity regime is critical to calibrate properly. In this paper, we aim to add candidate Gaia benchmark stars inside of this metal-poor gap. We began with a sample of 21 metal-poor stars which was reduced to 10 stars by requiring accurate photometry and parallaxes, and high-resolution archival spectra. The procedure used to determine the stellar parameters was similar to the previous works in this series for consistency. The difference was to homogeneously determine the angular diameter and effective temperature (Teff) of all of our stars using the Infrared Flux Method utilizing multi-band photometry. The surface gravity (logg) was determined through fitting stellar evolutionary tracks. The [Fe/H] was determined using four different spectroscopic methods fixing the Teff and logg from the values determined independent of spectroscopy.
4967. Gaia FPR at ESA
- ID:
- ivo://esavo/gaia/csfpr
- Title:
- Gaia FPR at ESA
- Short Name:
- GAIA FPR
- Date:
- 07 Feb 2024 10:18:23
- Publisher:
- European Space Agency
- Description:
- These tables, part of the Gaia Focused Product Release (FPR), have an entry for every Gaia observed source as listed in the Main Database accumulating catalogue version from which the catalogue release has been generated. The FPR contains the following products: astrometry and photometry from engineering images taken in the Omega Centauri region; an environment analysis of quasars in search of gravitational lenses; extended radial velocity epoch data for Long Period Variables (LPVs); Diffuse Interstellar Bands (DIBs) from aggregated RVS spectra; and updated astrometry for Solar System objects.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A59
- Title:
- Gaia-FUN-SSO network. Apophis campaign
- Short Name:
- J/A+A/583/A59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO . The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4, Cat. I/322) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A165
- Title:
- Gaia GraL. III. New lensed systems
- Short Name:
- J/A+A/622/A165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia GraL catalogue of clusters is composed of 2,129,659 clusters consisting of three or four stationary sources from Gaia DR2. Each cluster is assigned a discriminant value, called the extremely randomized trees probability, that reflects its ability to be matched to the image positions and relative magnitudes produced through simulations of gravitational lens systems.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A56
- Title:
- Gaia GraL. II. Known multiply imaged quasars
- Short Name:
- J/A+A/618/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to its spatial resolution the ESA/Gaia space mission offers a unique opportunity to discover new multiply-imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions. Aims : In this paper, we address the detection of the known multiply-imaged quasars from the Gaia Data Release 2 and determine the astrometric and photometric properties of the individually detected images found in the Gaia DR2 catalogue. We have compiled an exhaustive list of quasar gravitational lenses from the literature to search for counterparts in the Gaia Data Release 2. We then analyze the astrometric and photometric properties of these Gaia's detections. To highlight the tremendous potential of Gaia at the sub-milliarcsecond level we finally perform a simple Bayesian modeling of the well-known gravitational lens system HE0435-1223, using Gaia Data Release 2 and HST astrometry. From 478 known multiply imaged quasars, 200 have at least one image found in the Gaia Data Release 2. Among the 41 known quadruply-imaged quasars of the list, 26 have at least one image in the Gaia Data Release 2, 12 of which are fully detected (2MASX J01471020+4630433, HE 0435-1223, SDSS1004+4112, PG1115+080, RXJ1131-1231, 2MASS J11344050-2103230, 2MASS J13102005-1714579, B1422+231, J1606-2333, J1721+8842, WFI2033-4723, WGD2038-4008), 6 have three counterparts, 7 have two and 1 has only one. As expected, the modeling of HE0435-1223 shows that the model parameters are significantly better constrained when using Gaia astrometry compared to HST astrometry, in particular the relative positions of the background quasar source and the centroid of the deflector. The Gaia sub-milliarcsecond astrometry also significantly reduces the parameter correlations. Besides providing an up-to-date list of multiply imaged quasars and their detection in the Gaia DR2, this paper shows that more complex modeling scenarios will certainly benefit from Gaia sub-milliarcsecond astrometry.