g-Mode Oscillations in Hot B Subdwarf Stars

Observations from space with CoRoT and Kepler have revealed the rich pulsation spectra that characterize the long period hot B subdwarf (sdB) pulsators of the V1093 Her type. These evolved and compact helium core burning stars can develop low amplitude oscillations with periods in the range ∼ 1 − 4 hours that correspond to low degree, mid to high order g-modes. These modes have the property to penetrate deep inside the star, down to the boundary of the central convective core. They are consequently particularly interesting as asteroseismic probes. Here we briefly review how the g-modes behave in sdB stars, focusing in particular on the seismic signatures coming from the core itself. We also briefly summarize the first seismic results obtained from space data in pioneering efforts to exploit the potential of long period sdB pulsators as deep probes of the core structure.