The observational signatures of convectively excited gravity modes in main-sequence stars

Joshua H. Shiode, Eliot Quataert, Matteo Cantiello, Lars Bildsten

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

We predict the flux and surface velocity perturbations produced by convectively excited gravity modes (g-modes) in main-sequence stars. Core convection in massive stars can excite g-modes to sufficient amplitudes to be detectable with high-precision photometry by Kepler and Convection, Rotation and planetary Transits (CoRoT), if the thickness of the convective overshoot region is ≲30 per cent of a pressure scale height. The g-modes manifest as excess photometric variability, with amplitudes of ~10 μmag at frequencies ≲10 μHz (0.8 d-1) near the solar metallicity zero-age main sequence. The flux variations are largest for stars with M ≳ 5M⊙, but are potentially detectable down to M ~ 2-3M⊙. During the main-sequence evolution, radiative damping decreases such that ever lower frequency modes reach the stellar surface and flux perturbations reach up to ~100 μmag at the terminal-age main sequence. Using the same convective excitation model, we confirm previous predictions that solar gmodes produce surface velocity perturbations of≲0.3mm s-1. This implies that stochastically excited g-modes are more easily detectable in the photometry of massive main-sequence stars than in the Sun.

Original languageEnglish (US)
Pages (from-to)1736-1745
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume430
Issue number3
DOIs
StatePublished - 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Convection
  • Stars: interiors
  • Stars: oscillations

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