MS2 UE7b: Evolution of Galaxies

Joachim Köppen, Strasbourg, 2012/13

We live on Earth and circle around the Sun, which in a rather ordinary star in the Milky Way Galaxy, which is quite an ordinary spiral galaxy among the other zillions in the Universe. We understand extremely well the motions of the planets around the Sun. We know very well that stars shine because in their interiors they make heavier element by nuclear fusion and that at the end of their life they return some of these nuclear products to the interstellar medium, from which the next generation of stars will be born. Thus the different chemical compositions of stars in a galaxy indicate their age. Stars are like fossils which permit to learn about the evolution of a galaxy and the processes that formed it. We have some ideas about how galaxies are formed and how they evolve, but we do not yet understand the various physical processes that may play a role. Studying stars and gas is easy in our and nearby galaxies, but more difficult for objects far-away. Thus, our understanding of galaxies is continually being improved by observations as well as by theory.

Thus course will first cover those - more solid - subjects which are essential to obtain and interpret information about galaxies (determination of abundances in gas and stars, what we know about stars and nuclear synthesis). With this rather firm base, we then deal with stellar populations (IMF, SFR) and the evolution of the elements in a galaxy, and to explain the observations. While we shall not deal with the kinematics of stars in this course, the overall gas dynamics involved in an evolving galaxy needs to be addressed, which leads to the modern approach to treat both chemistry and dynamics in a more consistent way. The course aims to give an overview of essential observational facts and theoretical approaches, as well as of the problems, accuracies and uncertainties in the various aspects of the subject.

The plan ...

• 7 nov 12, 10-12 (amphi), Observed Properties of Galaxies
• 14 nov 12, 10-12 (amphi), Determination of abundances from Gas
• 21 nov 12, 10-12 (amphi), Determination of abundances from Stars
• 28 nov 12, 10-12 (amphi), Review of Stellar Structure and Evolution
• 12 dec 12, 10-12 (amphi), Nucleosynthesis in stars and the Big Bang
• 19 dec 12, 10-12 (amphi), IMF, SFR, SFH
• 9 jan 13, 10-12 (salle de cours), Chemical Evolution: Solar Neighbourhood
• 16 jan 13, 10-12 (amphi), Abundance Gradients, Mass-Metallicity Relation
• 23 jan 13, 10-12 (amphi), Galaxy Formation, Monolithic Collapse
• 30 jan 13, 10-12 (amphi), Chemodynamical Approach

pdfs of the lectures

• Observed Properties of Galaxies
• Determination of abundances from Gas
• Determination of abundances from Stars
• Review of Stellar Structure and Evolution
• Nucleosynthesis in stars and the Big Bang
• IMF, SFR, SFH
• Chemical Evolution: Solar Neighbourhood
• Abundance Gradients, Mass-Metallicity Relation
• Galaxy Formation, Monolithic Collapse
• Chemodynamical Approach

Homework I (please return before Christmas):

• Instructions
• data sets for Emmanuelle: 30 40 52
• data sets for Florie: 35 42 56
• data sets for Oriane: 30 42 52
• data sets for Simon: 30 40 52
• Solutions

Homework II (please return before 25 January):

• Instructions
• Solutions

links to useful simulations

• Airglow Spectrum depicts a typical observed optical spectrum of the night sky.
• Optical Stellar Spectra from the library of stellar spectra by Jacoby, Hunter, and Christian (Astrophys.J.Suppl.Ser., 56, 257 (1984)).
• The formation of an Absorption Line in a stellar atmosphere.
• Plasma Diagnostics interprets the emission line spectrum of ionized gaseous nebulae to get temperature, density, and the element abundances.
• Solar Photospheric Abundances gives the data from Asplund et al. (2005).

• Decomposition of Rotation Curves of disk galaxies into the visible and dark matter components. By Chris Mihos and colleagues at Case Western Reserve University
• Various Initial Mass Functions of the stars can be displayed.
• One Zone Model of chemical evolution with arbitrary rates for the star formation, gas infall and gas outflows, and with user-defined metallicity dependent yield for the chemical elements.
• Chemical evolution of a Galactic Disk computes radial abundance profiles.
• Stellar Population is a Monte Carlo simulation of a population of stars, born according to some specified star formation history. It also shows the computed evolutionary paths of any star between 0.8 and 120 solar masses in the Hertzsprung-Russell diagram.
• Collapse of a spherical selfgravitating gas cloud

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last update: Oct. 2012 J.Köppen