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.

doi:10.1093/mnras/stw2903

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.

Authors

Barry Smalley b.smalley@keele.ac.uk

V. Antoci

D. L. Holdsworth

D. W. Kurtz

S. J. Murphy

P. De Cat

D. R. Anderson

G. Catanzaro

A. Collier Cameron

Coel Hellier c.hellier@keele.ac.uk

Pierre Maxted p.maxted@keele.ac.uk

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.

Citation

Smalley, B., Antoci, V., L. Holdsworth, D., W. Kurtz, D., J. Murphy, S., De Cat, P., …J. Wheatley, P. (2017). Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP. Monthly Notices of the Royal Astronomical Society, 465(3), 2662-2670. https://doi.org/10.1093/mnras/stw2903

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