Amplitude modulation in δ Sct stars: statistics from an ensemble of Kepler targets
Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE, UK
2 Department of Astronomy, University of Texas, Austin, TX 78712, USA
3 Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia
4 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Aarhus C, DK-8000 Denmark
⋆ e-mail: email@example.com
Published online: 27 October 2017
The results of a search for amplitude modulation of pulsation modes in 983 δ Sct stars, which have effective temperatures between 6400 ⩽ Teff ⩽ 10 000 K in the Kepler Input Catalogue and were continuously observed by the Kepler Space Telescope for 4 yr, are presented. A total of 603 δ Sct stars (61.3 per cent) are found to exhibit at least one pulsation mode that varies significantly in amplitude over 4 yr. Furthermore, it is found that amplitude modulation is not restricted to a specific region within the classical instability strip in the HR diagram, therefore its cause is not necessarily dependent on stellar parameters such as Teff or log g. On the other hand, many δ Sct stars show constant pulsation amplitudes demonstrating that the cause of pulsational non-linearity in these stars is not well understood.
© Owned by the authors, published by EDP Sciences, 2017
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