Theory and evidence of global Rossby waves in upper main-sequence stars: r-mode oscillations in many Kepler stars
Article
Article Title | Theory and evidence of global Rossby waves in upper main-sequence stars: r-mode oscillations in many Kepler stars |
---|---|
ERA Journal ID | 1074 |
Article Category | Article |
Authors | Saio, Hideyuki (Author), Kurtz, Donald W. (Author), Murphy, Simon J. (Author), Antoci, Victoria L. (Author) and Lee, Umin (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 474 (2), pp. 2774-2786 |
Number of Pages | 13 |
Year | 2017 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stx2962 |
Web Address (URL) | https://academic.oup.com/mnras/article/474/2/2774/4638544 |
Abstract | Asteroseismic inference from pressure modes (p modes) and buoyancy, or gravity, modes (g modes) is ubiquitous for stars across the Hertzsprung–Russell diagram. Until now, however, discussion of r modes (global Rossby waves) has been rare. Here we derive the expected frequency ranges of r modes in the observational frame by considering the visibility of these modes. We find that the frequencies of r modes of azimuthal order m appear as groups at slightly lower frequency than m times the rotation frequency. Comparing the visibility curves for r modes with Fourier amplitude spectra of Kepler light curves of upper main-sequence B, A, and F stars, we find that r modes are present in many γ Dor stars (as first discovered by Van Reeth et al.), spotted stars, and so-called heartbeat stars, which are highly eccentric binary stars. We also find a signature of r modes in a frequently bursting Be star observed by Kepler. In the amplitude spectra of moderately to rapidly rotating γ Dor stars, r-mode frequency groups appear at lower frequency than prograde g-mode frequency groups, while in the amplitude spectra of spotted early A to B stars, groups of symmetric (with respect to the equator) r-mode frequencies appear just below the frequency of a structured peak that we suggest represents an approximate stellar rotation rate. In many heartbeat stars, a group of frequencies can be fitted with symmetric m = 1 r modes, which can be used to obtain rotation frequencies of these stars. |
Keywords | Binaries: eclipsing; Stars: early-type; Stars: oscillations; Stars: rotation; Stars: variables: general; Starspots; Astrophysics - Solar and Stellar Astrophysics |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | Tohoku University, Japan |
University of Central Lancashire, United Kingdom | |
University of Sydney | |
Aarhus University, Denmark | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q73vw/theory-and-evidence-of-global-rossby-waves-in-upper-main-sequence-stars-r-mode-oscillations-in-many-kepler-stars
Download files
47
total views37
total downloads0
views this month0
downloads this month