Spectroscopy of hot ? Doradus and A–F hybrid Kepler candidates close to the hot border of the d Scuti instability strip

Smalley

Abstract

If ? Dor-type pulsations are driven by the convective blocking mechanism, a convective envelope at a sufficient depth is essential. There are several hot ? Dor and hybrid star candidates in which there should not be an adequate convective envelope to excite the ? Dor-type oscillations. The existence of these hot objects needs an explanation. Therefore, we selected, observed, and studied 24 hot ? Dor and hybrid candidates to investigate their properties. The atmospheric parameters, chemical abundances, and vsin i values of the candidates were obtained using medium-resolution (R = 46 000) spectra taken with the Fibre-fed Échelle Spectrograph instrument mounted at the Nordic Optical Telescope. We also carried out frequency analyses of the Kepler long- and short-cadence data to determine the exact pulsation contents. We found only five bona fide hot ? Dor and three bona fide hot hybrid stars in our sample. The other 16 stars were found to be normal ? Dor, d Sct, or hybrid variables. No chemical peculiarity was detected in the spectra of the bona fide hot ? Dor and hybrid stars. We investigated the interplay between rotation and pulsational modes. We also found that the hot ? Dor stars have higher Gaia luminosities and larger radii compared to main-sequence A–F stars.

Citation

Smalley. (2020). Spectroscopy of hot ? Doradus and A–F hybrid Kepler candidates close to the hot border of the d Scuti instability strip. Monthly Notices of the Royal Astronomical Society, 4518 - 4532. https://doi.org/10.1093/mnras/staa399

• Acceptance Date: Feb 4, 2020
• Publication Date: Feb 11, 2020
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Publisher: Oxford University Press
• Pages: 4518 - 4532
• DOI: https://doi.org/10.1093/mnras/staa399
• Keywords: stars: abundances, stars: atmospheres, stars: general, stars: oscillations, stars: rotation
• Publisher URL: https://academic.oup.com/mnras/article/493/3/4518/5733179