Galactic Chemical Evolution of Heavy Elements: From Barium to Europium

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.

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GO UPSTREAM OF THE "MILKY WAY": ORIGIN OF HEAVY ELEMENTS INFERRED FROM GALACTIC CHEMICAL EVOLUTION

The R-Process ◽

10.1142/9789812702470_0015 ◽

2004 ◽

Author(s):

Y. ISHIMARU ◽

S. WANAJO ◽

N. PRANTZOS ◽

W. AOKI ◽

S. G. RYAN

Keyword(s):

Chemical Evolution ◽

Milky Way ◽

Heavy Elements ◽

Galactic Chemical Evolution

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Heavy Element Nucleosynthesis

EPJ Web of Conferences ◽

10.1051/epjconf/201818401007 ◽

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.

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The Early History of Our Galaxy: Chemical Evolution

Symposium - International Astronomical Union ◽

10.1017/s0074180900024396 ◽

1974 ◽

Vol 58 ◽

pp. 141-156

Author(s):

Manuel Peimbert

Keyword(s):

Chemical Evolution ◽

Stellar Evolution ◽

Local Group ◽

Early History ◽

The Other ◽

Heavy Elements ◽

Galactic Chemical Evolution ◽

Chemical Abundance ◽

Iron Abundance ◽

History Of

A general review is given of chemical abundance determinations; particular emphasis is given to abundances of galactic and extragalactic metal-poor objects since presumably they represent the abundances of the primeval material from which our Galaxy was formed. The following results are stressed: (a) most of the helium present in the galaxies of the local group as well as in other galaxies was produced before these objects were formed, (b) the heavy elements were produced mainly as the result of stellar evolution, (c) there is a chemical abundance gradient in our Galaxy and, by analogy with other galaxies, it is expected to be steeper near the nucleus, (d) the carbon and oxygen content of our Galaxy increased at a rate different from the metals, reaching their present abundance earlier than the other heavy elements, and (e) the increase of the iron abundance in the disk of our Galaxy with time has been small while that of carbon is negligible; furthermore, as a group the super-metal-rich stars correspond to the old disk population. Several models of galactic chemical evolution are reviewed.

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Strontium in the era of Gaia and LAMOST

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313006765 ◽

2013 ◽

Vol 9 (S298) ◽

pp. 409-409

Author(s):

Camilla J. Hansen ◽

Elisabetta Caffau ◽

Maria Bergemann

Keyword(s):

Chemical Evolution ◽

Spectral Resolution ◽

Neutron Capture ◽

Local Thermodynamic Equilibrium ◽

Heavy Elements ◽

Galactic Chemical Evolution ◽

Non Local ◽

Formation And Evolution ◽

Open Question ◽

Insight Into

AbstractThe formation and evolution of the heavy neutron-capture elements (Z > 37) are to date not well understood. Therefore, abundance and galactic chemical evolution (GCE) studies of these heavy elements may carry key information to this open question. Strontium (Sr) is one of the two heavy elements (Sr and Ba) that show intrinsically very strong absorption lines even in extremely metal-poor stars (and remains detectable at low spectral resolution). Hence, the 4077 Å Sr II line provides a unique insight into the behaviour of heavy neutron-capture elements at all metallicities and resolutions. Here the focus is on strontium, its 3D and NLTE (non-local thermodynamic equilibrium) corrections, as well as chemical evolution.

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Galactic Chemical Evolution of the s Process from AGB Stars

Publications of the Astronomical Society of Australia ◽

10.1071/as08053 ◽

2009 ◽

Vol 26 (3) ◽

pp. 153-160 ◽

Cited By ~ 25

Author(s):

Alessandra Serminato ◽

Roberto Gallino ◽

Claudia Travaglio ◽

Sara Bisterzo ◽

Oscar Straniero

Keyword(s):

Solar System ◽

Chemical Evolution ◽

Asymptotic Giant Branch ◽

Heavy Elements ◽

Agb Stars ◽

Galactic Chemical Evolution ◽

Element Analysis ◽

Residual Method ◽

The Galaxy ◽

Process Element

AbstractWe follow the chemical evolution of the Galaxy for the s elements using a Galactic chemical evolution (GCE) model, as already discussed by Travaglio et al. (1999, 2001, 2004), with a full updated network and refined asymptotic giant branch (AGB) models. Calculations of the s contribution to each isotope at the epoch of the formation of the solar system is determined by following the GCE contribution by AGB stars only. Then, using the r-process residual method we determine for each isotope their solar system r-process fraction, and recalculate the GCE contribution of heavy elements accounting for both the s and r process. We compare our results with spectroscopic abundances at various metallicities of [Sr,Y,Zr/Fe], of [Ba,La/Fe], of [Pb/Fe], typical of the three s-process peaks, as well as of [Eu/Fe], which in turn is a typical r-process element. Analysis of the various uncertainties involved in these calculations are discussed.

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