3D hydrodynamic simulations of massive main-sequence stars-II. Convective excitation and spectra of internal gravity waves

William Thompson, Falk Herwig, Paul R. Woodward, Huaqing Mao, Pavel Denissenkov, Dominic M. Bowman, Simon Blouin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Recent photometric observations of massive stars have identified a low-frequency power excess which appears as stochastic low-frequency variability in light-curve observations. We present the oscillation properties of high-resolution hydrodynamic simulations of a star performed with the PPMstar code. The model star has a convective core mass of and approximately half of the envelope simulated. From this simulation, we extract light curves from several directions, average them over each hemisphere, and process them as if they were real photometric observations. We show how core convection excites waves with a similar frequency as the convective time-scale in addition to significant power across a forest of low and high angular degree l modes. We find that the coherence of these modes is relatively low as a result of their stochastic excitation by core convection, with lifetimes of the order of 10s of days. Thanks to the still significant power at higher l and this relatively low coherence, we find that integrating over a hemisphere produces a power spectrum that still contains measurable power up to the Brunt-Väisälä frequency. These power spectra extracted from the stable envelope are qualitatively similar to observations, with the same order of magnitude yet lower characteristic frequency. This work further shows the potential of long-duration, high-resolution hydrodynamic simulations for connecting asteroseismic observations to the structure and dynamics of core convection and the convective boundary.

Original languageEnglish (US)
Pages (from-to)1316-1337
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume531
Issue number1
DOIs
StatePublished - Jun 1 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s).

Keywords

  • asteroseismology
  • convection
  • hydrodynamics
  • methods: numerical
  • stars: interiors
  • stars: massive

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