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arXiv · 2002.04669

Spectroscopy of hot Gamma Doradus and A-F hybrid Kepler candidates close to the hot border of the Delta Scuti instability strip

F. Kahraman Alicavus·E. Poretti·G. Catanzaro·B. Smalley·E. Niemczura·M. Rainer·G. Handler
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Abstract

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

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F. Kahraman Alicavus, E. Poretti, G. Catanzaro, B. Smalley, E. Niemczura, M. Rainer, G. Handler. 2020-02-11. Spectroscopy of hot Gamma Doradus and A-F hybrid Kepler candidates close to the hot border of the Delta Scuti instability strip. https://doi.org/10.1093/mnras/staa399

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