1210.5525 (Joshua H. Shiode et al.)

The Observational Signatures of Convectively Excited Internal Gravity Waves in Main Sequence Stars    [PDF]

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

We predict the flux and surface velocity perturbations produced by convectively excited internal gravity waves (IGWs or g-modes) in main sequence stars. Core convection in massive stars can excite IGWs to sufficient amplitudes to be detectable with high precision photometry by Kepler and CoRoT, if the thickness of the convective overshoot region is < 30 per cent of a pressure scale height. The IGWs manifest as excess photometric variability, with amplitudes of ~ 10 micromagnitudes at frequencies < 10 microHz (0.8 1/d) near the solar metallicity zero-age main sequence. The flux variations are largest for stars with M > 5 solar masses, but are potentially detectable down to M ~ 2 - 3 solar masses . 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 micromagnitudes at the terminal-age main sequence. Using the same convective excitation model, we confirm previous predictions that solar IGWs produce surface velocity perturbations of < 0.3 mm/s. This implies that stochastically excited IGWs are more easily detectable in the photometry of massive main sequence stars than in the Sun.

View original: http://arxiv.org/abs/1210.5525