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Paper: Non Active Stars: The Ca II (H+K) Basal Flux
Volume: 472, New Quests in Stellar Astrophysics III: A Panchromatic View of Solar-like Stars, With and Without Planets
Page: 263
Authors: Pérez-Martínez, M. I.; Schröder, K. P
Abstract: We present the analysis of the Ca II (H+K) chromospheric emission line of a sample of 76 evolved stars. The spectra were taken from the UVES Paranal Observatory Project, which consists in a library of high resolution spectra. Since our main purpose is to obtain the basal flux, which is associated with non magnetic processes, we used a sample of evolved stars. We used the PHOENIX atmospheric models as photospheric templates in order to measure the chromospheric contribution only. Thanks to the large grid of atmospheric models, we were able to determine surface gravity (log g) and effective temperature (Teff) for every star in our sample, and we found that the goodness of fit between the atmospheric models and the stellar spectra decreases with decreasing temperature, indicating the existence of missing factors, i.e. metallicity, to take into account in the modelling of cool stars. Finally, we obtained a basal flux that agrees within the errors with previous results in the literature; this assures us the correct use of the PHOENIX atmospheric models as photospheric templates.
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