Rapidly-oscillating {\it TESS} A--F main sequence stars: are the roAp stars a distinct class?

Abstract

From sector 1--44 {\em TESS} observations, 19 new roAp stars, 103 ostensibly non-peculiar stars with roAp-like frequencies and 617 $\delta$~Scuti stars with independent frequencies typical of roAp stars were found. Examination of all chemically peculiar stars observed by {\em TESS} resulted in the discovery of 199 Ap stars which pulsate as $\delta$~Sct or $\gamma$~Dor variables. The fraction of pulsating Ap stars is the same as the fraction of pulsating chemically normal stars. There is no distinct separation in frequency or radial order between chemically peculiar $\delta$~Sct stars and roAp stars. In fact, all the features which originally distinguished roAp from $\delta$~Sct stars in the past have disappeared. There is no reason to assume that the high frequencies in roAp stars are driven by a different mechanism from the high frequencies in chemically normal stars. However, chemically peculiar stars are far more likely to pulsate with high frequencies. The term "roAp" should be dropped: all roAp stars are normal $\delta$~Scuti stars.

19 pages, 11 figures, 5 tables

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Cited by in corpus (4)

• Gaia Data Release 3: Cross-match of Gaia sources with variable objects from the literature
• Periodic variable A-F spectral type stars in the northern TESS continuous viewing zone
• Unveiling $\delta$ Scuti and $\gamma$ Doradus Hybrid Pulsation of HD 53166 and HD 53349 Plus Rich Frequencies in HD 52788 -- Catalogs of 70552 $\delta$ Sct and 8080 $\gamma$ Dor
• Periodic variable A-F spectral type stars in the southern TESS continuous viewing zone