HD 42477: coupled r modes, g modes, and a p mode in an A0Vnne star

ABSTRACT Several studies have shown that a number of stars pulsating in p modes lie between the β Cep and δ Sct instability strips in the Hertzsprung–Russell (HR) Diagram. At present, there is no certain understanding of how p modes can be excited in this Teff range. The goal of this work is to disp...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Monthly notices of the Royal Astronomical Society 2023-05, Vol.521 (3), p.4765-4774
Hauptverfasser: Kurtz, D W, Jayaraman, R, Sowicka, P, Handler, G, Saio, H, Labadie-Bartz, J, Lee, U
Format: Artikel
Sprache:eng
Online-Zugang:Volltext bestellen
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:ABSTRACT Several studies have shown that a number of stars pulsating in p modes lie between the β Cep and δ Sct instability strips in the Hertzsprung–Russell (HR) Diagram. At present, there is no certain understanding of how p modes can be excited in this Teff range. The goal of this work is to disprove the conjecture that all stars pulsating in p modes and lying in this Teff range are the result of incorrect measurements of Teff, contamination, or the presence of unseen cooler companions lying in the δ Sct instability strip (given the high binary fraction of stars in this region of the HR Diagram). Using TESS data, we show that the A0Vnne star HD 42477 has a single p mode coupled to several r modes and/or g modes. We rule out a contaminating background star with a pixel-by-pixel examination, and we essentially rule out the possibility of a companion δ Sct star in a binary. We model the pulsations in HD 42477, and suggest that the g modes are excited by overstable convective core modes. We also conjecture that the single p mode is driven by coupling with the g modes, or that the oblateness of this rapidly-rotating star permits driving by He ii ionization in the equatorial region.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stad858