The chemical compositions of Galactic disc F and G dwarfs
Reads0
Chats0
TLDR
In this article, photospheric abundances for 27 elements from carbon to europium in 181 F and G dwarfs from a differential local thermodynamic equilibrium (LTE) analysis of high-resolution and high signal-to-noise ratio spectra were presented.Abstract:
Photospheric abundances are presented for 27 elements from carbon to europium in 181 F and G dwarfs from a differential local thermodynamic equilibrium (LTE) analysis of high-resolution and high signal-to-noise ratio spectra. Stellar effective temperatures (T eff) were adopted from an infrared flux method calibration of Stromgren photometry. Stellar surface gravities (g) were calculated from Hipparcos parallaxes and stellar evolutionary tracks. Adopted T eff and g values are in good agreement with spectroscopic estimates. Stellar ages were determined from evolutionary tracks. Stellar space motions (U , V , W ) and a Galactic potential were used to estimate Galactic orbital parameters. These show that the vast majority of the stars belong to the Galactic thin disc. Relative abundances expressed as (X/Fe) generally confirm previously published results. We give results for C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu. The α elements - O, Mg, Si, Ca and Ti - show (α/Fe) to increase slightly with decreasing (Fe/H). Heavy elements with dominant contributions at solar metallicity from the s-process show (s/Fe) to decrease slightly with decreasing (Fe/H). Scatter in (X/Fe) at a fixed (Fe/H) is entirely attributable to the small measurement errors, after excluding the few thick disc stars and the s-process-enriched CH subgiants. Tight limits are set on 'cosmic' scatter. If a weak trend with (Fe/H) is taken into account, the composition of a thin disc star expressed as (X/Fe) is independent of the star's age and birthplace for elements contributed in different proportions by massive stars (Type II supernovae), exploding white dwarfs (Type Ia supernovae) and asymptotic red giant branch stars. By combining our sample with various published studies, comparisons between thin and thick disc stars are made. In this composite sample, thick disc stars are primarily identified by their V LSR in the range −40 to −100 km s −1 . These are very old stars with origins in the inner Galaxy and metallicities (Fe/H) −0.4. At the same (Fe/H), the sampled thin disc stars have V LSR ∼ 0k m s −1 , and are generally younger with a birthplace at about the Sun's Galactocentric distance. In the range −0.35 (Fe/H) −0.70, well represented by present thin and thick disc samples, (X/Fe) of the thick disc stars is greater than that of thin disc stars for Mg, Al, Si, Ca, Ti and Eu. (X/Fe) is very similar for the thin and thick disc for - notably - Na and iron-group elements. Barium ((Ba/Fe)) may be underabundant in thick relative to thin disc stars. These results extend previous ideas about composition differences between the thin and thick disc.read more
Citations
More filters
Journal ArticleDOI
The Chemical Composition of the Sun
TL;DR: The solar chemical composition is an important ingredient in our understanding of the formation, structure, and evolution of both the Sun and our Solar System as discussed by the authors, and it is an essential refer...
Journal ArticleDOI
A grid of MARCS model atmospheres for late-type stars. I. Methods and general properties
TL;DR: In this article, an extensive grid of spherically-symmetric models (supplemented with plane-parallel ones for the highest surface gravities), built on up-to-date atomic and molecular data, is presented.
Journal ArticleDOI
The Geneva-Copenhagen survey of the Solar neighbourhood - Ages, metallicities, and kinematic properties of ~14 000 F and G dwarfs
Birgitta Nordström,Birgitta Nordström,Michel Mayor,Johannes Andersen,J. Holmberg,Frederic Pont,Bjarne Rosenkilde Jørgensen,E. H. Olsen,Stéphane Udry,N. Mowlavi +9 more
TL;DR: In this article, the authors presented and discussed new determinations of metallicity, rotation, age, kinematics, and Galactic orbits for a com- plete, magnitude-limited, and kinematically unbiased sample of 16 682 nearby F and G dwarf stars.
Journal ArticleDOI
The Galaxy in Context: Structural, Kinematic, and Integrated Properties
TL;DR: In this paper, the authors review the key integrated, structural and kinematic parameters of the Galaxy, and point to uncertainties as well as directions for future progress, and show that the Galaxy is a luminous (L⋆) barred spiral with a central box/peanut bulge, a dominant disk, and a diffuse stellar halo.
Journal ArticleDOI
Abundance Variations within Globular Clusters
TL;DR: Abundance variations within globular clusters (GCs) and of GC stars with respect to field stars are important diagnostics of a variety of physical phenomena, related to the evolution of individual stars, mass transfer in binary systems, and chemical evolution in high density environments as mentioned in this paper.
References
More filters
Journal ArticleDOI
Standard Solar Composition
Nicolas Grevesse,A. J. Sauval +1 more
TL;DR: In this article, the current status of our knowledge of the chemical composition of the Sun is reviewed, essentially derived from the analysis of the solar photospheric spectrum, and a comparison of solar and meteoritic abundances confirms that there is a very good agreement between the two sets of abundances.
Standard Solar Composition
Nicolas Grevesse,A. J. Sauval +1 more
TL;DR: In this article, the current status of our knowledge of the chemical composition of the Sun is reviewed, essentially derived from the analysis of the solar photospheric spectrum, and a comparison of solar and meteoritic abundances confirms that there is a very good agreement between the two sets of abundances.
Journal ArticleDOI
The NextGen Model Atmosphere Grid for 3000 ≤ Teff ≤ 10,000 K
Peter H. Hauschildt,E. Baron +1 more
TL;DR: The NextGen Model Atmosphere Grid for low-mass stars for effective temperatures larger than 3000 K was proposed in this article. But it is not suitable for the analysis of star spectra.
Journal ArticleDOI
The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$
Peter H. Hauschildt,E. Baron +1 more
TL;DR: The NextGen Model Atmosphere Grid for low mass stars for effective temperatures larger than 3.5°C was presented in this article, with the same basic model assumptions and input physics as the VLMS part of the NextGen grid so that the complete grid can be used.
Journal ArticleDOI
The New Galaxy: Signatures of Its Formation
TL;DR: The formation and evolution of galaxies is one of the great outstanding problems of astrophysics as discussed by the authors, and a detailed physical picture where individual stellar populations can be associated with (tagged to) elements of the protocloud is far beyond our current understanding.
Related Papers (5)
The Evolution and Explosion of Massive Stars. II. Explosive Hydrodynamics and Nucleosynthesis
S. E. Woosley,Thomas A. Weaver +1 more