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

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

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

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 < 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.
Original languageEnglish
Pages (from-to)2662-2670
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume465
Issue number3
Early online date10 Nov 2016
DOIs
Publication statusPublished - 1 Mar 2017

Keywords

  • Asteroseismology
  • Techniques: photometric
  • Stars: chemically peculiar
  • Stars: oscillations
  • Stars: variables: δ Scuti

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