Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP
Date Issued
2017
Author(s)
Smalley, B.
•
Antoci, V.
•
Holdsworth, D. L.
•
Kurtz, D. W.
•
Murphy, S. J.
•
De Cat, P.
•
Anderson, D. R.
•
•
Collier Cameron, A.
•
Hellier, C.
•
Maxted, P. F. L.
•
Norton, A. J.
•
Pollacco, D.
•
•
West, R. G.
•
Wheatley, P. J.
Abstract
We present the results of a study of a large sample of A and Am stars with spectral types from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and light curves from Wide Area Search for Planets (WASP). We find that, unlike normal A stars, δ Sct pulsations in Am stars are mostly confined to the effective temperature range 6900 < {{T_eff}} < 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.
Volume
465
Issue
3
Start page
2662
Issn Identifier
0035-8711
Ads BibCode
2017MNRAS.465.2662S
Rights
open.access
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