Abundance ratios & ages of stellar populations in HARPS-GTO sample

2017 ◽  
Vol 12 (S330) ◽  
pp. 156-159 ◽  
Author(s):  
E. Delgado Mena ◽  
M. Tsantaki ◽  
V. Zh. Adibekyan ◽  
S. G. Sousa ◽  
N. C. Santos ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Thin Disk ◽  
Thick Disk ◽  
Heavy Elements ◽  
Galactic Chemical Evolution ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Different Populations ◽  
Search Program ◽  
Cu And Zn

AbstractIn this work we present chemical abundances of heavy elements (Z>28) for a homogeneous sample of 1059 stars from HARPS planet search program. We also derive ages using parallaxes from Hipparcos and Gaia DR1 to compare the results. We study the [X/Fe] ratios for different populations and compare them with models of Galactic chemical evolution. We find that thick disk stars are chemically disjunt for Zn adn Eu. Moreover, the high-alpha metal-rich population presents an interesting behaviour, with clear overabundances of Cu and Zn and lower abundances of Y and Ba with respect to thin disk stars. Several abundance ratios present a significant correlation with age for chemically separated thin disk stars (regardless of their metallicity) but thick disk stars do not present that behaviour. Moreover, at supersolar metallicities the trends with age tend to be weaker for several elements.

scholarly journals OCCASO – III. Iron peak and α elements of 18 open clusters. Comparison with chemical evolution models and field stars

2019 ◽  
Vol 490 (2) ◽  
pp. 1821-1842 ◽  
Author(s):  
L Casamiquela ◽  
S Blanco-Cuaresma ◽  
R Carrera ◽  
L Balaguer-Núñez ◽  
C Jordi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Nucleosynthesis ◽  
Solar Abundances ◽  
Red Giant

ABSTRACT The study of open-cluster chemical abundances provides insights on stellar nucleosynthesis processes and on Galactic chemo-dynamical evolution. In this paper we present an extended abundance analysis of 10 species (Fe, Ni, Cr, V, Sc, Si, Ca, Ti, Mg, O) for red giant stars in 18 OCCASO clusters. This represents a homogeneous sample regarding the instrument features, method, line list and solar abundances from confirmed member stars. We perform an extensive comparison with previous results in the literature, and in particular with the Gaia FGK Benchmark stars Arcturus and $\mu$-Leo. We investigate the dependence of [X/Fe] with metallicity, Galactocentric radius (6.5 kpc < RGC < 11 kpc), age (0.3 Gyr < Age < 10 Gyr), and height above the plane (|z| < 1000 pc). We discuss the observational results in the chemo-dynamical framework, and the radial migration impact when comparing with chemical evolution models. We also use APOGEE DR14 data to investigate the differences between the abundance trends in RGC and |z| obtained for clusters and for field stars.

scholarly journals Modelling the chemical evolution of the Milky Way

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Francesca Matteucci
Keyword(s):  
Observational Data ◽  
Chemical Evolution ◽  
Predictive Power ◽  
Milky Way ◽  
Thin Disk ◽  
Thick Disk ◽  
Stellar Nucleosynthesis

AbstractIn this review, I will discuss the comparison between model results and observational data for the Milky Way, the predictive power of such models as well as their limits. Such a comparison, known as Galactic archaeology, allows us to impose constraints on stellar nucleosynthesis and timescales of formation of the various Galactic components (halo, bulge, thick disk and thin disk).

Galactic Chemical Evolution of Heavy Elements: From Barium to Europium

1999 ◽  
Vol 521 (2) ◽  
pp. 691-702 ◽  
Author(s):  
Claudia Travaglio ◽  
Daniele Galli ◽  
Roberto Gallino ◽  
Maurizio Busso ◽  
Federico Ferrini ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Heavy Elements ◽  
Galactic Chemical Evolution

scholarly journals Volatiles and refratories in solar analogs: No terrestial planet connection

2010 ◽  
Vol 6 (S276) ◽  
pp. 422-423 ◽  
Author(s):  
Jonay I. González Hernández ◽  
Garik Israelian ◽  
Nuno C. Santos ◽  
Sergio Sousa ◽  
Elisa Delgado-Mena ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Planetary Systems ◽  
Galactic Chemical Evolution ◽  
Chemical Abundances ◽  
Volatile Elements ◽  
High Quality ◽  
Refractory Elements ◽  
Solar Abundances ◽  
Solar Analogs ◽  
Very High

AbstractWe have analysed very high-quality HARPS and UVES spectra of 95 solar analogs, 24 hosting planets and 71 without detected planets, to search for any possible signature of terrestial planets in the chemical abundances of volatile and refractory elements with respect to the solar abundances.We demonstrate that stars with and without planets in this sample show similar mean abundance ratios, in particular, a sub-sample of 14 planet-host and 14 “single” solar analogs in the metallicity range 0.14 < [Fe/H] < 0.36. In addition, two of the planetary systems in this sub-sample, containing each of them a super-Earth-like planet with masses in the range ~ 7-11 Earth masses, have different volatile-to-refratory abundance ratios to what would be expected from the presence of a terrestial planets.Finally, we check that after removing the Galactic chemical evolution effects any possible difference in mean abundances, with respect to solar values, of refratory and volatile elements practically dissappears.

scholarly journals Binary Fractions of G and K Dwarf Stars Based on Gaia EDR3 and LAMOST DR5: Impacts of the Chemical Abundances

2021 ◽  
Vol 922 (2) ◽  
pp. 211
Author(s):  
Zexi Niu ◽  
Haibo Yuan ◽  
Song Wang ◽  
Jifeng Liu
Keyword(s):  
Thin Disk ◽  
Thick Disk ◽  
Chemical Abundances ◽  
Dwarf Stars ◽  
Halo Stars ◽  
Binary Formation ◽  
Data Release ◽  
Inclination Angles ◽  
Thin And Thick Disks ◽  
Single Epoch

Abstract Based on the large volume Gaia Early Data Release 3 and LAMOST Data Release 5 data, we estimate the bias-corrected binary fractions of the field late G and early K dwarfs. A stellar locus outlier method is used in this work, which works well for binaries of various periods and inclination angles with single-epoch data. With a well-selected, distance-limited sample of about 90,000 GK dwarfs covering wide stellar chemical abundances, it enables us to explore the binary fraction variations with different stellar populations. The average binary fraction is 0.42 ± 0.01 for the whole sample. Thin-disk stars are found to have a binary fraction of 0.39 ± 0.02, thick-disk stars have a higher one of 0.49 ± 0.02, while inner halo stars possibly have the highest binary fraction. For both the thin- and thick-disk stars, the binary fractions decrease toward higher [Fe/H], [α/H], and [M/H] abundances. However, the suppressing impacts of [Fe/H], [α/H], and [M/H] are more significant for the thin-disk stars than those for the thick-disk stars. For a given [Fe/H], a positive correlation between [α/Fe] and the binary fraction is found for the thin-disk stars. However, this tendency disappears for the thick-disk stars. We suspect that it is likely related to the different formation histories of the thin and thick disks. Our results provide new clues for theoretical works on binary formation.

scholarly journals Abundances of Iron-Group Elements in Planetary Nebulae and Consequences for Chemical Enrichment

2016 ◽  
Vol 12 (S323) ◽  
pp. 82-85
Author(s):  
Harriet L. Dinerstein ◽  
T. R. Geballe ◽  
N. C. Sterling
Keyword(s):  
Emission Line ◽  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Infrared Emission ◽  
Thick Disk ◽  
Galactic Chemical Evolution ◽  
Iron Group ◽  
Chemical Enrichment ◽  
Group Species

AbstractWe have developed a method for determining elemental Fe-group abundances in planetary nebulae using an infrared emission line of Zn, the least refractory Fe-group species. Many planetary nebulae, particularly those of the Milky Way’s thick disk and bulge, display subsolar [Fe/H] (as inferred from Zn) although their abundances of α elements such as O, S, and Ar are nearly solar. We discuss the implications for determining enhancements of species synthesized by the progenitor star during the AGB (e.g.,s-process products), and for galactic chemical evolution in view of the metallicity dependence of AGB nucleosynthetic yields.

scholarly journals Simple MCBR models of chemical evolution: An application to the thin and the thick disk

2012 ◽  
pp. 35-51 ◽  
Author(s):  
R. Caimmi
Keyword(s):  
Chemical Evolution ◽  
Thin Disk ◽  
Thick Disk ◽  
Abundance Distribution ◽  
Oxygen Abundance ◽  
Extremum Point ◽  
Monotonic Trend ◽  
Linear Fit ◽  
Hydrodynamical Simulations ◽  
Fractional Mass

Simple multistage closed-(box+reservoir) (MCBR) models of chemical evolution, formulated in an earlier attempt, are extended to the limit of dominant gas inflow or outflow with respect to gas locked up into long-lived stars and remnants. For an assigned empirical differential oxygen abundance distribution (EDOD), which can be linearly fitted, a family of theoretical differential oxygen abundance distribution (TDOD) curves is built up with the following prescriptions: (i) the initial and the ending points of the linear fit are common to all curves; (ii) the flow parameter k ranges from an extremum point to ? ?, where negative and positive k correspond to inflow and outflow, respectively; (iii) the cut parameter ?O ranges from an extremum point (which cannot be negative) to the limit (?O) ? related to |k|? + ?. For curves with increasing ?O, the gas mass fraction locked up into long-lived stars and remnants is found to attain a maximum and then decrease towards zero as |k|? + ? while the remaining parameters show a monotonic trend. The theoretical integral oxygen abundance distribution (TIOD) is also expressed. An application is made to the EDOD deduced from two different samples of disk stars, for both the thin and the thick disk. The constraints on formation and evolution are discussed in the light of the model. The evolution is tentatively subdivided into four stages, namely: assembling (A), formation (F), contraction (C), equilibrium (E). The EDOD related to any stage is fitted by all curves where 0 ? ?O ? (?O) ? for inflowing gas and (?O) ? ? ?O ? 1.2 for outflowing gas, with a single exception related to the thin disk (A stage), where the range of fitting curves is restricted to 0.35 ? ?O ? (?O) ?. The F stage may safely be described by a steady inflow regime (k= -1), implying a flat TDOD, in agreement with the results of hydrodynamical simulations. Finally, (1) the change of fractional mass due to the extension of the linear fit to the EDOD, towards both the (undetected) low-metallicity and high-metallicity tail, is evaluated and (2) the idea of a thick disk - thin disk collapse is discussed, in the light of the model.

scholarly journals Heavy Element Nucleosynthesis

2018 ◽  
Vol 184 ◽  
pp. 01007
Author(s):  
Mounib F. El Eid
Keyword(s):  
Chemical Evolution ◽  
Neutron Capture ◽  
Heavy Element ◽  
Slow Neutron ◽  
Heavy Elements ◽  
Galactic Chemical Evolution ◽  
Physical Processes ◽  
The Galaxy ◽  
R Process

This contribution deals with the important subject of the nucleosynthesis of heavy elements in the Galaxy. After an overview of several observational features, the physical processes responsible mainly for the formation of heavy elements will be described and linked to possible stellar sites and to galactic chemical evolution. In particular, we focus on the neutron-capture processes, namely the s-process (slow neutron capture) and the r-process (rapid neutron capture) and discuss some problems in connection with their sites and their outcome. The aim is to give a brief overview on the exciting subject of the heavy element nucleosynthesis in the Galaxy, emphasizing its importance to trace the galactic chemical evolution and illustrating the challenge of this subject.

Sign in / Sign up

Export Citation Format

Share Document