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Atomic and Molecular Physics for Astonomical Observations by
James Colgan
13 May 2003 Atomic and molecular processes are the key production mechanisms for many of the emission and absorption lines observed by space and ground based telescopes in several wavelength regions. These processes occur in different types of astrophysical plasmas found in stars, the interstellar medium, regions near galactic centers, and over a range of plasma densities and temperatures. A brief overview will first be given of our groups current efforts to provide atomic data for use by fusion plasma modelers. In recent years, a Scientific Discovery Through Advanced Computing (SciDAC) award from the DOE has helped us to provide quality atomic data for a variety of collisional processes such as electron-impact ionization and excitation, photoionization, and ion-impact excitation and charge transfer. The various pertubative and non-pertubative methods used to calculate these atomic processes will be discussed. This data is placed into atomic databases such as Atomic Data and Analysis Structure (ADAS) which is used for collisional-radiative modeling by both fusion and astrophysical plasma modelers. The second part of this presentation will focus on how atomic physics calculations can provide meaningful data which can be used to help interpret astronomical observations. Two main examples will be given of specific areas in which atomic theory and experiment can work together to the benefit of astrophysical modeling: 1) The calculation of electron-impact ionization cross sections and rate coefficients for ions of astrophysical interest. Comparisons of such calculations with experimental measurements will be discussed and analysis of the implications for astrophysical modeling will be explored. 2) The progress of a project set up to calculate dielectronic recombination rate coefficients for a large number of atomic ions over a wide range of electron temperatures. Such processes are the dominant electron-ion recombination processes in many astrophysical plasmas.
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