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

Smalley, B.; Antoci, V.; L. Holdsworth, D.; W. Kurtz, D.; J. Murphy, S.; De Cat, P.; R. Anderson, D.; Catanzaro, G.; Collier Cameron, A.; Hellier, C.; F. L. Maxted, P.; J. Norton, A.; Pollacco, D.; Ripepi, V.; G. West, R.; J. Wheatley, P.

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


Authors

V. Antoci

D. L. Holdsworth

D. W. Kurtz

S. J. Murphy

P. De Cat

D. R. Anderson

G. Catanzaro

A. Collier Cameron

A. J. Norton

D. Pollacco

V. Ripepi

R. G. West

P. J. Wheatley



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, d Sct pulsations in Am stars are mostly confined to the effective temperature range 6900<Teff<76006900<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 ?-mechanism, which is expected to be suppressed by gravitational settling in these stars.

Journal Article Type Article
Acceptance Date Nov 6, 2016
Online Publication Date Nov 10, 2016
Publication Date 2017-03
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 465
Issue 3
Pages 2662-2670
DOI https://doi.org/10.1093/mnras/stw2903
Keywords asteroseismology, stars, chemically peculiar stars, oscillations, variables, delta scuti techniques, photometric, astrophysics
Publisher URL http://dx.doi.org/10.1093/mnras/stw2903

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