Internal dynamics from asteroseismology for two sdB pulsators in close binary systems

Since their discovery eleven years ago, short-period pulsating sdB stars have proved their potential for quantitative asteroseismological studies. We have recently updated our astero- seismic diagnostic tools in order to incorporate the effects of stellar rotation on pulsations, assuming various internal rotation laws. It is possible, with these new tools, to determine the internal rotation profile of two short-period pulsating sdB stars residing in close binary systems, namely Feige 48 and PG 1336 -018. They exhibit orbital periods of 9.024 h and 2.424 h respectively, as measured from spectroscopy. For the two stars, we show that spin-orbit synchronism is reached from the surface down to ˜ 0.22 R∗ and 0.55 RxE2x88x97 , respectively. The rotation of deeper layers cannot be inferred with the type of modes p-modes observed in short-period pulsating sdB stars. These results can potentially provide new elements to test tidal friction theories, particularly the angular momentum transport, in close binary systems.