ASTROPHYSICS LABORATORY II

General purpose of the course Astrophysics Laboratory II is to give the student the tools necessary for the acquisition, reduction and interpretation of spectroscopic and spectropolarimetric data at high spectral resolution. With reference to stellar atmospheres and environments, the problem of numerical solution of the radiative transport equation will be addressed. The basis for determining stellar parameters from the comparison of observed and theoretical spectra will be provided. It will also be shown how these methods and techniques can be applied to laboratory plasmas where, under controlled temperature and density conditions, plasma spectroscopy can allow even the determination of fundamental atomic constants.

The aim of the course is to contribute to: Convert the theoretical knowledge into applications and tools aimed at measuring physical parameters. Consolidate the understanding of the interconnections between theoretical and experimental / observational aspects, even in interdisciplinary areas. The development of critical skills in the analysis and interpretation of both observational and experimental scientific results. Boost, by means of the design and implementation of tools and software, the analytical capacity understood as a subdivision of a complex process into fundamental parts and in the identification of their mutual influences and consequentiality. Develop the ability to evaluate results by comparing them with what is reported in the literature. Develop the language necessary for communicating the topics covered by this course. Strengthen the ability to report on the activities carried out both orally and in writing.

In addition to lectures, the course will consists of:

Spectroscopic and spectropolarimetric observations with the instrumentation of the Catania Astrophysical Observatory (mount Etna)

Exercises in data reduction with IRAF: http://iraf.noao.edu

Exercises in numerically calculating stellar atmospheres with ATLAS: http://www.oact.inaf.it/castelli/castelli/sources/atlas9codes.html

Exercises in numerically solving the radiative transfer equation in LTE with SYNTHE: http://www.oact.inaf.it/castelli/castelli/sources/synthe.html

Exercises in numerically solving the radiative transfer equation in presence of magnetic fields with COSSAM: https://www.oact.inaf.it/leone/Stift/ada2012_eu/cossam/index.html

Exercises in numerically calculating the non-LTE plasma emissivity with CHIANTI: http:/https://www.chiantidatabase.org/

Note: should the circumstances require online or blended teaching, appropriate modifications to what is hereby stated may be introduced, in order to achieve the main objectives of the course.

Echelle Spectroscopy:

Echelle Spectrographs. Methods for acquisition and reduction of spectrocopic and spectropolariemtric data.

Determination of Stellar Parameters:

Numerical solution of Stellar Atmospheres.

Numerical solution of the Radiative Transfer Equation in the hypothesis of Local Thermodynamic Equilibrium.

Determination of stellar parameters by comparison between observed spectra and numerical simulations: radial velocity, rotational velocity, Effective temperature, surface gravity, micro and macro turbulence, and chimica abundances. Magnetic fields.

Emissivity from non equilibrium plasmas. Diagnostic applications: Density and temperature measurements.

Kitchin C.R., Astrophysical Techniques - Publisher Institute of Physics Publishing

Gray D.F., The observation and analysis of stellar spectra – Cambridge Astrophysics Series

Mihalas D., - Stellar Atmospheres. -San Francisco: W. H. Freeman & Company

Landi Degl'Innocenti, Landolfi - Polarization in Spectral Lines - Kluwer Academic Publishers