An astrophysical interpretation of the remarkable g-mode frequency groups of the rapidly rotating γ Dor star, KIC 5608334

Saio, Hideyuki, Bedding, Timothy R, Kurtz, Donald Wayne orcid iconORCID: 0000-0002-1015-3268, Murphy, Simon J, Antoci, Victoria L, Shibahashi, Hiromoto, Li, Gang and Takata, Masao (2018) An astrophysical interpretation of the remarkable g-mode frequency groups of the rapidly rotating γ Dor star, KIC 5608334. Monthly Notices of the Royal Astronomical Society, 477 (2). pp. 2183-2195. ISSN 1365-2966

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Official URL: https://doi.org/10.1093/mnras/sty784

Abstract

The Fourier spectrum of the γ-Dor variable KIC 5608334 shows remarkable frequency groups at ∼3, ∼6, ∼9, and 11–12 d−1. We explain the four frequency groups as prograde sectoral g modes in a rapidly rotating star. Frequencies of intermediate-to-high radial order prograde sectoral g modes in a rapidly rotating star are proportional to |m| (i.e. ν∝|m|) in the corotating frame as well as in the inertial frame. This property is consistent with the frequency groups of KIC 5608334 as well as the period versus period-spacing relation present within each frequency group, if we assume a rotation frequency of 2.2 d−1, and that each frequency group consists of prograde sectoral g modes of |m| = 1, 2, 3, and 4, respectively. In addition, these modes naturally satisfy near-resonance conditions νi ≈ νj + νk with mi = mj + mk. We even find exact resonance frequency conditions (within the precise measurement uncertainties) in many cases, which correspond to combination frequencies.


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