AIMS OF GALACTIC CHEMICAL EVOLUTION STUDIES check / constrain our understanding of stellar nucleosynthes .e. stellar yields), either statistically (mean, dispersion) or individual objects To establish a chronology of events in a given system e.g. when metallicity reached a given value, or when some stellar source (SNIa, AGB etc.) became important contributor to the abundance of a given isotope / element To infer how a system was formed (Star Formation Rate, large scale gas mouvements) e.g. slow infall of gas in case of solar neighborhood
AIMS OF G ALACTIC C HEMICAL E VOLUTION STUDIES. To check / constrain our understanding of stellar nucleosynthesis (i.e. stellar yields), either statistically (mean, dispersion) or in individual objects. To establish a chronology of events in a given system - PowerPoint PPT Presentation
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AIMS OF GALACTIC CHEMICAL EVOLUTION STUDIES
To check / constrain our understanding of stellar nucleosynthesis(i.e. stellar yields), either statistically (mean, dispersion) or in
individual objects
To establish a chronology of events in a given systeme.g. when metallicity reached a given value, or when some
stellar source (SNIa, AGB etc.) became important contributorto the abundance of a given isotope / element
To infer how a system was formed (Star Formation Rate, large scale gas mouvements)
e.g. slow infall of gas in case of solar neighborhood
THE SOLAR NEIGHBORHOOD
SLOW INFALL ( = 7 Gyr) to fix G-dwarf problem, SNIa to account for [Fe/O] evolution
PREDICTIONS: D evolution, evolution of abundances (depends on yields)
AGE-METALLICITY METALLICITYDISTRIBUTION
Woosley and Weaver 1995, Overproduction factors of elements in massive stars
ABUNDANCES AT SOLAR SYSTEM FORMATION(Massive stars: Woosley+Weaver 1995; Intermediate mass stars: van den Hoek+Gronewegen 1997;
SNIa: Iwamoto et al. 2000)
AGES OF GLOBULAR CLUSTERS
AGES OFHALO STARS
Marquez and Schuster 1994
Salaris and Weiss 2002
Norris and Ryan 1991
INFALL
OUTFLOW
AGE – METALLICITY IN THE GALACTIC HALO
Note: Instantaneous mixing approximation probably invalid at early times
Stars of mass M > 2 Mʘ (Lifetime < 1 Gyr)enriched the Galaxy during the halo phase
NOTE: PRIMARIES VS SECONDARIES
1) CHEMICAL EVOLUTION (yield: IMF integrated or individual stars)
PRIMARY: yield yP independent of Z
SECONDARY: yield yS proportional to Z
2) STELLAR NUCLEOSYNTHESIS (yield from individual stars)
PRIMARY: from H, He and their products (C,O)(yield not necessarily Z independent!)
SECONDARY: from some metal at stellar formation(yield not necessarily proportional to Z!)