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We present differential stellar population models, which allow improved determinations of the ages, iron and alpha-element abundances of old stellar populations from spectral fitting. These new models are calibrated at solar abundances…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 C. J. Walcher , P. Coelho , A. Gallazzi , S. Charlot

We extend the grid of NLTE models presented in Paper II to explore variations in abundance pattern in two ways: 1) The adoption of the Asplund et al. (2009) (GASS10) abundances, 2) For stars of metallicity, [M/H], of -0.5, the adoption of a…

Solar and Stellar Astrophysics · Physics 2015-06-15 C. Ian Short , Eamonn A. Campbell

This paper presents a study of the chemical compositions in cool gas around a sample of 27 intermediate-redshift galaxies. The sample comprises 13 massive quiescent galaxies at z=0.40-0.73 probed by QSO sightlines at projected distances…

Astrophysics of Galaxies · Physics 2017-01-18 Fakhri S. Zahedy , Hsiao-Wen Chen , Jean-René Gauthier , Michael Rauch

The third Gaia data release contains, beyond the astrometry and photometry, dispersed light for hundreds of millions of sources from the Gaia prism spectra (BP and RP) and the spectrograph (RVS). This data release opens a new window on the…

We present Cu and Zn abundances for 38 FGK stars, mostly dwarfs, spanning a metallicity range between solar and [Fe/H] =-3. The abundances were obtained using Kurucz's local thermal equilibrium (LTE) model atmospheres and the near-UV lines…

Astrophysics · Physics 2009-11-10 G. Bihain , G. Israelian , R. Rebolo , P. Bonifacio , P. Molaro

We construct a model of H$\alpha$ emitters (HAEs) based on a semi-analytic galaxy formation model, the New Numerical Galaxy Catalog ($\nu^2$GC). In this paper, we report our estimate for the field variance of the HAE distribution. By…

We investigate the debated "sulphur discrepancy" found among metal-poor stars of the Galactic halo with [Fe/H] < -2. This discrepancy stems in part from the use of two different sets of sulphur lines, the very weak triplet at 8694-95 A and…

Astrophysics · Physics 2016-08-30 Andreas J. Korn , Nils Ryde

Although anomalous surface abundances are often observed in A-type main-sequence stars (known as chemically peculiar stars; e.g., metallic line stars or Am stars), our understanding about the behavior of aluminium is still insufficient.…

Solar and Stellar Astrophysics · Physics 2023-10-18 Yoichi Takeda

Using the Livermore X-ray Spectral Synthesizer, which calculates spectral models of highly charged ions based on HULLAC atomic data, we investigate the temperature, density, and photoexcitation dependence of the I(11.92 A)/I(11.77 A) line…

Astrophysics · Physics 2007-05-23 Christopher W. Mauche , Duane A. Liedahl , Kevin B. Fournier

Recent spectroscopic explorations of large Galactic stellar samples stars have revealed the existence of red giants with [$\alpha$/Fe] ratios that are anomalously high, given their relatively young ages. We revisit the GALAH DR3 survey to…

Solar and Stellar Astrophysics · Physics 2022-12-21 S. Borisov , N. Prantzos , C. Charbonnel

I present a review of chemical evolution models of the solar neighborhood. I give special attention to the necessary ingredients to reproduce the observed [Xi/Fe] ratios in nearby metal and super metal rich stars, and to the chemical…

Astrophysics · Physics 2007-05-23 L. Carigi

Solar flares show highly unusual spectra, in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral…

Solar and Stellar Astrophysics · Physics 2017-06-28 Fatima Rubio da Costa , Lucia Kleint

We used the spectroscopic and astrometric data provided from the GALAH DR2 and Gaia DR2, respectively, for a large sample of stars to investigate the behaviour of the [$\alpha$/Fe] abundances via two procedures, i.e. kinematically and…

Astrophysics of Galaxies · Physics 2019-11-13 S. Karaali , S. Bilir , E. Yaz Gokce , O. Plevne

We present a detailed and uniform study of oxygen abundances in 155 solar type stars, 96 of which are planet hosts and 59 of which form part of a volume-limited comparison sample with no known planets. EW measurements were carried out for…

Astrophysics · Physics 2009-11-11 A. Ecuvillon , G. Israelian , N. C. Santos , N. G. Shchukina , M. Mayor , R. Rebolo

We search for an optimal filter design for the estimation of stellar metallicity, based on synthetic photometry from Gaia XP spectra convolved with a series of filter-transmission curves defined by different central wavelengths and…

We analyze the ASCA spectra accumulated within ~100 kpc radii of 12 of the brightest groups of galaxies. Upon fitting isothermal models (1T) jointly to the ASCA SIS and GIS spectra we obtain fits for most groups that are of poor or at best…

Astrophysics · Physics 2016-08-30 David A. Buote

We describe the atomic and molecular data that were used for the abundance analyses of FGK-type stars carried out within the Gaia-ESO Survey. We present an unprecedented effort to create a homogeneous line list, which was used by several…

The spatial distribution of elemental abundances in the disc of our Galaxy gives insights both on its assembly process and subsequent evolution, and on the stellar nucleogenesis of the different elements. Gradients can be traced using…

We present preliminary results for estimation of barium ([Ba/Fe]) and strontium ([Sr/Fe]) abundances ratios using medium-resolution spectra (1-2 {\AA}). We established a calibration between the abundance ratios and line indices for Ba and…

Solar and Stellar Astrophysics · Physics 2015-05-13 Monique Cruz , Silvia Rossi , Timothy C. Beers

The observations of FIR line and continuum spectra throughout the Galactic centre and in some regions of the disc are analysed in order to determine the physical conditions (densities, shock velocities, radiation parameters, etc.) and the…

Astrophysics of Galaxies · Physics 2015-05-27 M. Contini
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