69058 - Resolved Stellar Populations

Course Unit Page

Academic Year 2017/2018

Learning outcomes

The course presents the general overview of the observational properties of resolved stellar populations. At the end of the course the student is able to discuss the observational properties of simple (as galactic globular clusters)  and complex (galaxies)  stellar populations. He/she will acquire skills on both observational and theoretical astrophysical problems concerning resolved stellar populations, and will be able to identify the main indicators of metallicity, age and distance of stellar populations. The student learns to critically discuss the open questions about stellar populations, through short written notes and multi-media presentations.

Course contents

Evolutive sequences in the HR diagram: isochrones and evolutionary tracks. Connection between theory and observations: reddening, distance, bolometric corrections. 

Metallicity/age/distance indicators in resolved stellar populations. Galactic Globular clusters and their properties. The Main Sequence Turn-Off as age indicator. The color position and the shape of the Red Giant Branch. The distance indicators: The HB level, the RR-Lyrae luminosity, the RGB-tip, the RGB-Bump properties. The WD cooling sequences as age and distance indicator. The complex morphology of the Horizontal Branch. Properties of Simple Stellar Populations (SSP). Spectral Energy Distribution (SED). Fuel Consumption theorem. Phase transitions in SSP. Contribution to the integrated light of each evolutionary sequence. The stellar population in the Magellanic Clouds. Complex stellar populations. "Exotic" stellar populations and their link with globular cluster internal dynamics: blue straggler stars, optical companions to millisecond pulsars, intermediate-mass black holes. Note about collisional dynamics (mass segregation, energy equipartition, core collapse, gravothermic catastrophe) and King models.


The final exam can be prepared using the notes taken during the lessons and the Lecture Notes made available by the teacher every year at the AMS Campus site:



During the classes, the reading of several scientific papers is suggested. The papers can be downloaded at the dedicated web sites. For instance: http://cdsads.u-strasbg.fr/abstract_service.html


Additional text books useful for further detailed study are:

Evolution of stars and stellar populations - Salaris & Cassisi

An Introduction to modern Astrophysics - Carroll & Ostlie

Astrofisica stellare - V. Castellani

Astrophysics I. stars - Bowers& Deeming

Teaching methods

The course is made of 6 CFU, corresponding to 48 hours of front lectures. These are made with the support of power-point presentations and at the blackboard. The lessons include the explanation of astrophysical concepts specific to resolved stellar populations and observational astronomy, helped with images and graphs aimed at improving the comprehension.

The possibility of a final lab experience, aimed at constructing and interpreting color-magnitude diagrams using globular cluster stellar catalogs, will be agreed with the students at the beginning of the course.

Assessment methods

The final examination aims at verifying and evaluating the acquisition of the teaching goals. It consist in an oral assessment on all arguments discussed in the lectures.

Teaching tools

Lectures are supported by power-point presentations, which are updated and made available to the students every year on the dedicates AMS Campus web site:


Office hours

See the website of Barbara Lanzoni