1. Basic Concepts on Chemical Evolution Cesare Chiosi Department of Astronomy University of Padova, Italy

2. Aims To understand the pattern of abundances in the solar system, in the solar vicinity, in the Halo, Bulge, and Disk of the Milky Way, in external galaxies of different morplogical type, and finally in the Universe as a whole. An easy and difficult task at the same time!

3. Abundances Standard abundances in the solar system and solar vicinity (inside 0.5 Kpc radius) provide the richest information. Detailed compilations are available (Cameron, Anders & Grevesse….). Surprisingly abundances are fairly homogenous going from one site to another. The Cosmic Soupe tastes the same in all restaurants!! With obvious differences. Why? Need to know the amount of mass (total and in gas and stars) in the solar vicinity. highly controversial, say total 70 Mo /pc^2 (from dynamics), stars 25 Mo/pc^2, gas 6 Mo/pc^2

4. An old compilation but still…. Abundances are the relative number of atoms, gradients in dlogX/dR (R in kpc)

5. Abundance ratios (neglect the lines)  -enhancement problem

6. Metallicity Distribution G-Dwarf problem In the Disk virtually no star of low metallicity. In the Halo the opposite

7. Age-Metallicity relationship In reality the relationship is much more dispersed: at any age a large scatter in metallicity can be seen.

8. Present-day and Initial Mass Function in the Solar Vicinity The present day mass function is derived from the observed luminosity function

9. Passing from PDMF to IMF

10. Popular IMFs x and a positive numbers Salpeter Larson, Chabrier Other, more or less equivalent formulations have been proposed over the years

11. Need an assumption for  (t)

12. Simple Models Assumptions: Initial conditions Closure of the system: infall, outflow, radial flow, galactic winds Star formation rate  (t) Chemical Yields Mixing Let  T,  g,  s be the surface mass densities (or masses in general) of total baryonic matter, gas, and stars respectively ………

13. Basic Equations

14. Instantaneous recycling

15. The equation for gas becomes… … and that for abundances… Yi is the Key Quantity to be derived from stellar nucleosynthesis theory

16. Particular solutions Close-Box Model Primary versus secondary elements………………… In many circumstances, this type of solution is not particularly satisfactory when compared to observational data

17. Particular solutions Open Model The abundances tend to the Yield This type of model is often in better agreement with the observational data, e.g. the G-dwarf Problem in the Solar Vicinity

18. Most popular model Predicts the right temporal dependence for  t  to explain G-Dwarf (Chiosi, 1980)

19. The Chemical Yields: prescription The chemical yields are based on the state-of-the-art of stellar evolution and stellar nucleasynthesis theory. Important parameters and quantities to remember are M He, Mco, Mr, and Mej (this latter for each elemental species)

20. Prescription 1 (single stars)

21. Prescription 2 (single stars)

22. Prescription 3 (single stars)

23. Prescription 4 (binary stars)

24. Prescription 5 (binary stars)

25. Prescription 6 (binary stars)

26. Prescription 7 (final remarks)

27. Structure Diagrams

28. Element by element…..

29. Element by element Is this theory successful ? Yes

30. Results: O/Fe

31. Results: alpha/Fe

32. Results: C/Fe

33. Results: N/Fe

34. Remarks It explains G-Dwarf problem Age-Metallicity Gross chemical features of galaxies of different morphological type It has been used in many different contexts and environments