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

The R-Process ◽  
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

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.

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 Chemical Evolution of R-process Elements in the Hierarchical Galaxy Formation

2015 ◽  
Vol 11 (S317) ◽  
pp. 318-319
Author(s):  
Yutaka Komiya ◽  
Toshikazu Shigeyama
Keyword(s):  
Neutron Star ◽  
Chemical Evolution ◽  
Galaxy Formation ◽  
Milky Way ◽  
Galactic Chemical Evolution ◽  
Halo Stars ◽  
R Process ◽  
Process Elements ◽  
Milky Way Halo

AbstractThe main astronomical source of r-process elements has not yet been identified. One plausible site is neutron star mergers (NSMs). From the perspective of Galactic chemical evolution, however, it has been pointed out that the NSM scenario is incompatible with observations. Recently, Tsujimoto & Shigeyama (2014) pointed out that NSM ejecta can spread into much larger volume than ejecta from a supernova. We re-examine the chemical evolution of r-process elements under the NSM scenario considering this difference in propagation of the ejecta. We find that the NSM scenario can be compatible with the observed abundances of the Milky Way halo stars.

scholarly journals Galactic Chemical Evolution

2003 ◽  
Vol 20 (4) ◽  
pp. 401-415 ◽  
Author(s):  
Brad K. Gibson ◽  
Yeshe Fenner ◽  
Agostino Renda ◽  
Daisuke Kawata ◽  
Hyun-chul Lee
Keyword(s):  
Boundary Condition ◽  
Galaxy Evolution ◽  
Chemical Evolution ◽  
Milky Way ◽  
State Of The Art ◽  
Galactic Chemical Evolution ◽  
Current State ◽  
Important Constraint

AbstractThe primary present-day observables upon which theories of galaxy evolution are based are a system’s morphology, dynamics, colour, and chemistry. Individually, each provides an important constraint to any given model; in concert, the four represent a fundamental (intractable) boundary condition for chemodynamical simulations. We review the current state-of-the-art semi-analytical and chemodynamical models for the Milky Way, emphasising the strengths and weaknesses of both approaches.

scholarly journals The Milky Way Halo and the First Stars: New Frontiers in Galactic Archaeology

2009 ◽  
Vol 5 (H15) ◽  
pp. 184-184
Author(s):  
Timothy C. Beers ◽  
Jason Tumlinson ◽  
Brian O'Shea ◽  
Carolyn Peruta ◽  
Daniela Carollo
Keyword(s):  
Chemical Evolution ◽  
Milky Way ◽  
Galactic Chemical Evolution ◽  
Joint Effort ◽  
First Stars ◽  
Large Samples ◽  
New Models ◽  
First Galaxies ◽  
The Relationship ◽  
Milky Way Halo

AbstractWe discuss plans for a new joint effort between observers and theorists to understand the formation of the Milky Way halo back to the first epochs of chemical evolution. New models based on high-resolution N-body simulations coupled to simple models of Galactic chemical evolution show that surviving stars from the epoch of the first galaxies remain in the Milky Way today and should bear the nucleosynthetic imprint of the first stars. We investigate the key physical influences on the formation of stars in the first galaxies and how they appear today, including the relationship between cosmic reionization and surviving Milky Way stars. These models also provide a physically motivated picture of the formation of the Milky Ways “outer halo,” which has been identified from recent large samples of stars from SDSS. The next steps are to use these models to guide rigorous gas simulations of Milky Way formation, including its disk, and to gradually build up the fully detailed theoretical “Virtual Galaxy” that is demanded by the coming generation of massive Galactic stellar surveys.

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.

scholarly journals The Early History of Our Galaxy: Chemical Evolution

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.

scholarly journals Galactic evolution of D, 3He and 4He

2009 ◽  
Vol 5 (S268) ◽  
pp. 431-440
Author(s):  
Donatella Romano
Keyword(s):  
Magnetic Fields ◽  
Chemical Evolution ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Evolution ◽  
Galactic Chemical Evolution ◽  
Low Mass Stars ◽  
Local Abundance ◽  
The Galaxy ◽  
Low Mass

AbstractThe uncertainties which still plague our understanding of the evolution of the light nuclides D, 3He and 4He in the Galaxy are described. Measurements of the local abundance of deuterium range over a factor of 3. The observed dispersion can be reconciled with the predictions on deuterium evolution from standard Galactic chemical evolution models, if the true local abundance of deuterium proves to be high, but not too high, and lower observed values are due to depletion onto dust grains. The nearly constancy of the 3He abundance with both time and position within the Galaxy implies a negligible production of this element in stars, at variance with predictions from standard stellar models which, however, do agree with the (few) measurements of 3He in planetary nebulae. Thermohaline mixing, inhibited by magnetic fields in a small fraction of low-mass stars, could in principle explain the complexity of the overall scenario. However, complete grids of stellar yields taking this mechanism into account are not available for use in chemical evolution models yet. Much effort has been devoted to unravel the origin of the extreme helium-rich stars which seem to inhabit the most massive Galactic globular clusters. Yet, the issue of 4He evolution is far from being fully settled even in the disc of the Milky Way.

scholarly journals Strontium in the era of Gaia and LAMOST

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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