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Related papers: Heavy element abundance patterns in hot DA white d…

200 papers

A total of 81 DA white dwarfs have been observed with the Cosmic Origins Spectrograph on the Hubble Space Telescope in a snapshot program. The targets were selected to be in the $T_{\rm eff}$ range from 17000 - 25000 K, where optical metal…

Solar and Stellar Astrophysics · Physics 2012-09-27 Detlev Koester , Boris Gänsicke , Jonathan Girven , Jay Farihi

We present a new version of the compiled catalogue of nearby stars for which was published the spectoscopically determined effective temperatures, surface gravities, and abundances of iron, magnesium, calcium, silicon, and titanium.…

Astrophysics · Physics 2007-10-25 T. V. Borkova , M. S. Katchieva , B. A. Marsakov , D. M. Pitkina

We present spectral analysis of the diffuse emission in the normal, isolated, moderate-Lx S0 NGC 1332, constraining both the temperature profile and the metal abundances in the ISM. The characteristics of the point source population and the…

Astrophysics · Physics 2009-11-10 Philip J. Humphrey , David A. Buote , Claude R. Canizares

Near-infrared photometry and spectroscopy is obtained for a heterogeneous sample of nearby white dwarfs with possible excess flux as identified primarily in the Two Micron All Sky Survey. Among the sample of 43 stars are a number of white…

Solar and Stellar Astrophysics · Physics 2012-06-06 J. Farihi

[Abridged abstract] We have performed an abundance analysis for 176 F- and G- dwarfs of the Galactic thick disk component. Using accurate radial velocities combined with $Hipparcos$ astrometry, kinematics (U, V, and W) and Galactic orbital…

Astrophysics · Physics 2009-11-13 Bacham E. Reddy , David L. Lambert , Carlos Allende Prieto

Abundances of five elements, Na, Mg, Al, Si, and Sr, are investigated for 44 very metal-poor stars (-4.0 < [Fe/H] < -1.5) in the Galactic halo system based on an Local Thermodinamic Equilibrium (LTE) analysis of high-resolution…

Abundances of 15 chemical elements have been derived for 28 F and 16 A stars members of the Hyades open cluster in order to set constraints on self-consistent evolutionary models including radiative and turbulent diffusion. A spectral…

Solar and Stellar Astrophysics · Physics 2015-05-19 M. Gebran , M. Vick , R. Monier , Luca Fossati

Abundances for Fe, O, and the alpha-elements (Mg, Si, Ca, and Ti) have been derived from high resolution spectra of a sample of about one hundred dwarfs with high precision parallaxes measured by HIPPARCOS. The stars have metal abundances…

Astrophysics · Physics 2007-05-23 R. G. Gratton , E. Carretta , G. Clementini , C. Sneden

Ultraviolet and optical spectra of the hydrogen-dominated atmosphere white dwarf star G238-44 obtained with FUSE, Keck/HIRES, HST/COS, and HST/STIS reveal ten elements heavier than helium: C, N, O, Mg, Al, Si, P, S, Ca, and Fe. G238-44 is…

Earth and Planetary Astrophysics · Physics 2022-12-21 Ted M Johnson , Beth L. Klein , D. Koester , Carl Melis , B. Zuckerman , M. Jura

High-resolution (R ~ 90,000) spectra of 34 nearby, young Sun-like stars were analyzed using stellar atmosphere models to estimate effective photosphere temperatures, surface gravities, and the abundance of certain heavy elements (C, Na, Mg,…

Astrophysics · Physics 2009-11-07 E. J. Gaidos , G. Gonzalez

Abundances of lithium, carbon, and oxygen have been derived using spectral synthesis for a sample of 249 bright F, G, and K Northern Hemisphere dwarf stars from the high-resolution spectra acquired with the VUES spectrograph at the Moletai…

Brown dwarf spectra are rich in information revealing of the chemical and physical processes operating in their atmospheres. We apply a recently developed atmospheric retrieval tool to an ensemble of late T-dwarf (600-800K) near infrared…

We present an abundance analysis of a sample of 33 hydrogen-rich (DA) white dwarfs. We have used archival high-resolution spectra to measure abundances of calcium, magnesium and iron in a set of 30 objects. In addition, we present…

Solar and Stellar Astrophysics · Physics 2015-05-20 Adela Kawka , Stephane Vennes , Frantisek Dinnbier , Helena Cibulkova , Peter Nemeth

Precise abundance ratios are determined for 94 dwarf stars with 5200 < Teff < 6300 K, -1.6 < [Fe/H] < -0.4, and distances D < 335 pc. Most of them have halo kinematics, but 16 thick-disk stars are included. Equivalent widths of atomic lines…

Astrophysics of Galaxies · Physics 2015-05-18 Poul E. Nissen , William J. Schuster

Lithium abundances in a sample of halo dwarfs have been redetermined by using the new T$_{eff}$ derived by Fuhrmann et al (1994) from modelling of the Balmer lines. These T$_{eff}$ are reddening independent, homogeneous and of higher…

Astrophysics · Physics 2007-05-23 P. Molaro , F. Primas , P. Bonifacio

The hot intra-cluster medium (ICM) is rich in metals, which are synthesized by supernovae (SNe) explosions and accumulate over time into the deep gravitational potential well of clusters of galaxies. Since most of the elements visible in…

Astrophysics of Galaxies · Physics 2016-08-24 François Mernier , Jelle de Plaa , Ciro Pinto , Jelle S. Kaastra , Peter Kosec , Yu-Ying Zhang , Junjie Mao , Norbert Werner

Using high-resolution echelle spectra obtained with Magellan/MIKE, we present a chemical abundance analysis of both stars in the planet-hosting wide binary system HD20782 + HD20781. Both stars are G dwarfs, and presumably coeval, forming in…

Earth and Planetary Astrophysics · Physics 2015-06-19 Claude E. Mack , Simon C. Schuler , Keivan G. Stassun , Joshua Pepper , John Norris

We present the abundances of the intermediate elements obtained by performing a stacked analysis of all the galaxy clusters in the archive of the X-ray telescope ASCA. We give the abundances of Fe, Si, S, and Ni as a function of cluster…

Astrophysics · Physics 2007-05-23 Wayne H. Baumgartner , Donald J. Horner , Richard F. Mushotzky

We report detailed analysis of high-resolution spectra of nine high velocity metal-rich dwarfs in the solar neighborhood. The stars are super metal-rich and 5 of them have [Fe/H]>=+0.4, making them the most metal-rich stars currently known.…

Astrophysics · Physics 2009-10-30 S. Castro , R. M. Rich , M. Grenon , B. Barbuy , J. K. McCarthy

We present a detailed calculation of model atmospheres for DA white dwarfs. Our atmosphere code solves the atmosphere structure in local thermodynamic equilibrium with a standard partial linearization technique, which takes into account the…

Astrophysics · Physics 2015-06-24 R. D. Rohrmann