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

Kurtz, Donald Wayne orcid iconORCID: 0000-0002-1015-3268, Jayaraman, R., Sowicka, P., Handler, G., Saio, H., Labadie-Bartz, J. and Lee, U. (2023) HD 42477: coupled r modes, g modes and a p mode in an A0Vnne star. Monthly Notices of the Royal Astronomical Society . ISSN 0035-8711

[thumbnail of AAM]
PDF (AAM) - Accepted Version
Available under License Creative Commons Attribution Non-commercial Share Alike.


Official URL: https://doi.org/10.1093/mnras/stad858


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.

Repository Staff Only: item control page