Delta Scuti (δ Sct)1 stars are opacity-driven pulsators with masses of 1.5–2.5M⊙, their pulsations resulting from the varying ionization of helium. In less massive stars2 such as the Sun, convection transports mass and energy through the outer 30 per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, with no firm theoretical basis, models predict that the convective envelope in δ Sct stars extends only about 1 per cent of the radius3, but with sufficient energy to excite solar-like oscillations4,5. This was not observed before the Kepler mission6, so the presence of a convective envelope in the models has been questioned. Here we report the detection of solar-like oscillations in the δ Sct star HD 187547, implying that surface convection operates efficiently in stars about twice as massive as the Sun, as the ad hoc models predicted.
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We thank the entire Kepler team, without whom these results would not be possible. V.A., G.Ha. and G.Ho. were supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung. V.A. also thanks L. Fossati for his help. A.M. acknowledges the funding of AstroMadrid, who was also supported by Spanish grants. T.R.B. and D.S. acknowledge support from the Australian Reseach Council. T.L was supported by the Austrian Agency for International Cooperation in Education and Research. K.U. acknowledges financial support from the Deutsche Forschungsgemeinschaft. Funding for this Discovery mission is provided by NASA’s Science Mission Directorate.
The authors declare no competing financial interests.
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Antoci, V., Handler, G., Campante, T. et al. The excitation of solar-like oscillations in a δ Sct star by efficient envelope convection. Nature 477, 570–573 (2011). https://doi.org/10.1038/nature10389
Journal of Astrophysics and Astronomy (2015)