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Accurate mean density and surface gravity of δ Scuti stars using Asteroseismology
Antonio García Hernández (Instituto de Astrofísica e Ciências do Espaço, U.Porto), Mário J. P. F. G. Monteiro (Instituto de Astrofísica e Ciências do Espaco, Universidade do Porto, CAUP), Zhao Guo (Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University), Daniel R. Reese (School of Physics and Astronomy, University of Birmingham / LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités), et al.
In the work we present here, we empirically demonstrate that a simple relation exists between a periodic pattern present in the frequency spectra of Delta Scuti stars and their mean density. This relation is homologous to that of solar-type stars. But the most important result is that this relation is indeed independent of the rotational velocity, becoming an ideal tool to constrain the pyhisical parameters of the star, even at high rotation rates. Moreover, we pushed the data one step further. Using also an estimation of the luminosity of each object, we demonstrate that it is possible, once the periodic pattern is determined, to derived the surface gravity of the star. The typical uncertainty we found for this quantity is the same as with high resolution spectroscopic data. This result might settle the degeneracy problem of the surface gravity determination with the spectra of A-type stars.