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Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP

Smalley, B.; Antoci, V.; Holdsworth, D. L.; Kurtz, D. W.; Murphy, S. J.; De Cat, P.; Anderson, D. R.; Catanzaro, G.; Cameron, A. Collier; Hellier, C.; Maxted, P. F. L.; Norton, A. J.; Pollacco, D.; Ripepi, V.; West, R. G. and Wheatley, P. J. (2017). Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP. Monthly Notices of the Royal Astronomical Society, 465(3) pp. 2662–2670.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1093/mnras/stw2903
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Abstract

We present the results of a study of a large sample of A and Am stars with spectral types from LAMOST and light curves from WASP. We find that, unlike normal A stars, δ Sct pulsations in Am stars are mostly confined to the effective temperature range 6900 <Teff <7600 K. We find evidence that the incidence of pulsations in Am stars decreases with increasing metallicism (degree of chemical peculiarity). The maximum amplitude of the pulsations in Am stars does not appear to vary significantly with metallicism. The amplitude distributions of the principal pulsation frequencies for both A and Am stars appear very similar and agree with results obtained from Kepler photometry. We present evidence that suggests turbulent pressure is the main driving mechanism in pulsating Am stars, rather than the κ-mechanism, which is expected to be suppressed by gravitational settling in these stars.

Item Type: Journal Item
Copyright Holders: 2016 The Authors
ISSN: 1365-2966
Keywords: asteroseismology – techniques; photometric – stars; chemically peculiar – stars; oscillations – stars; variables: δ Scuti
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 48826
Depositing User: Andrew Norton
Date Deposited: 07 Mar 2017 10:45
Last Modified: 16 May 2017 17:05
URI: http://oro.open.ac.uk/id/eprint/48826
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