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| SPAT0006-1 | Stellar atmospheres
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| Duration : | 20h Th, 10h Pr |
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| Credits/ECTS : |
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| Holder(s) : | Grégor Rauw |
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| Language : | French language |
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| Course contents : | Stellar spectra are formed in the stellar atmospheres and they contain a wealth of information on the physical conditions in these atmospheres. The goal of this course is to establish the link between the physical parameters on the one hand and the observable quantities (i.e. the spectra) on the other hand.
The course starts by reviewing the link between the Hertzsprung-Russell diagram and the stellar spectra. We then recall the fundamental notions of the interaction between matter and radiation and we introduce the concept of radiative transfer both in static and moving atmospheres. Stellar atmosphere codes aiming at the calculation of synthetic spectra rely on a number of assumptions (hydrostatic equilibrium, local thermodynamical equilibrium or absence of the latter) and we discuss these different hypotheses. We then review the different effects that determine the aspect of spectral lines (intrinsic width, broadening, rotational velocity, chemical composition). Finally, the main classification criteria that are used to assign a spectral type directly from the observations are presented. |
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| Course objective : | The purpose of this course is to explain the link between physical parameters of the stars and the characteristics of their spectra. When the students have completed this course they should understand how stellar properties such as the temperature, the luminosity, the chemical composition,... can be inferred from the analysis of stellar spectra. |
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| Prerequisites : | Good knowledge of physics (atomic spectroscopy) and mathematics. |
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| Workshops : | Several hands-on sessions are organized to illustrate the concepts introduced during the lectures. |
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| Organization : | 20 hours of lectures + 10 hours of hands-on sessions possibly including some computer labs (use of a computer code to determine the rotational velocity of a star).
The course will take place during the second semester. |
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| Written notes : | The lecture notes are provided in English. Hardcopies can be purchased for 5 euro, whilst the pdf file is available for free. |
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| Assessment : | The assessment will be done based on a written exam consisting of a theory question as well as one exercise. |
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| Contacts : | Gregor Rauw
Chargé de Cours
Institut d'Astrophysique et Géophysique, Bât. B5c,
Allée du 6 Août, 17
4000 Liège
Tel. +32-(0)4 366 9740
e-mail: rauw@astro.ulg.ac.be |
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| Remarks : | N/A |
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