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Line shape modeling for the characterization of magnetized plasmas in fusion research and astrophysics

Sede A. Riccò Via Santa Sofia 78, Catania

In this talk, we report on a selection of issues present in the elaboration of spectroscopic models for magnetized plasma diagnostic. A focus is put on tokamak edge and white dwarf atmosphere plasma conditions. In both cases, the observed spectra exhibit clean lines, either in absorption or in emission, denoting the presence of neutral species (atoms). An analysis of the line shape and intensity yields information on the plasma parameters provided a suitable physical model is used. We first discuss in detail the physical mechanisms underlying the broadening of the spectral lines due to the plasma microfield (Stark effect), and we next report on models and codes that have been developed in our group at the PIIM laboratory. Applications to the fitting of observed spectra – both in magnetic fusion and astrophysics – are presented. Motivated by current research trends, we also discuss specific issues related to the presence of strong external magnetic field (Zeeman effect etc.) and report on some recent works done in atomic physics for the improvement of line shape models.

Asteroseismic and spectroscopic study of NGC1647

Sede A. Riccò Via Santa Sofia 78, Catania

NGC1647 is a poorly studied open cluster, with considerable discrepancies in age reported in previous works. To improve the precision of its characterization, we applied HDBSCAN clustering in astrometric space, complemented by radial-velocity filtering, and identified 271 high-confidence cluster members. I will show as isochrone fitting to extinction-corrected photometry can provide a preliminary cluster age range. From TESS and K2 time-series photometry, we identified 95 periodic variables, including nine p-mode pulsators. By fitting stellar evolutionary models to these p-mode pulsators, we derived "asteroseismic" cluster parameters, Age and Metallicity. The seismic metallicity is consistent with spectroscopic estimates, while the derived age exhibits significantly higher precision than traditional isochrone-based results. Moreover, we analyzed LAMOST spectra using the ROTFIT tool and performed SED fitting to determine cluster extinction and conduct gyrochronology studies. This combined approach provides a refined benchmark for the fundamental parameters of NGC1647.