The excitation of solar-like oscillations in a δ Sct star by efficient envelope convection

• Published in: Nature (London) 2011-09, Vol.477 (7366), p.570-573
• Main Authors: Antoci, V., Handler, G., Campante, T. L., Thygesen, A. O., Moya, A., Kallinger, T., Stello, D., Grigahcène, A., Kjeldsen, H., Bedding, T. R., Lüftinger, T., Christensen-Dalsgaard, J., Catanzaro, G., Frasca, A., De Cat, P., Uytterhoeven, K., Bruntt, H., Houdek, G., Kurtz, D. W., Lenz, P., Kaiser, A., Van Cleve, J., Allen, C., Clarke, B. D.
• Format: Article
• Language: English
• Subjects: 639/33/34/867; Astrophysics; Humanities and Social Sciences; letter; multidisciplinary; Physics; Science; Science (multidisciplinary); Sciences of the Universe; Solar and Stellar Astrophysics
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature10389

Delta Scuti (δ Sct) 1 stars are opacity-driven pulsators with masses of 1.5–2.5 M ⊙ , their pulsations resulting from the varying ionization of helium. In less massive stars 2 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 radius 3 , but with sufficient energy to excite solar-like oscillations 4 , 5 . This was not observed before the Kepler mission 6 , 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.