2008CoAst.156...35V

In this paper, we exploit new photometric data for the short period pulsating sdB star PG 1605+072 gathered with the Canada- France-Hawaii Telescope. We identify some 65 frequency components, 19 of which are due to harmonics and nonlinear combinations of larger amplitude modes. We attempt to model the 46 remaining components in terms of a collection of rotationally-split frequency components in a relatively fast rotating pulsator and, thus, determine its rotation period. To do this, we must identify a priori the central (m=0) components of multiplets since the comparison is carried out with purely spherical models. We find that this a priori approach is not satisfactory and that no clear signature of a specific rotation period emerges. In the light of this result, we investigate another approach where PG 1605+072 is instead seen as a ``slow'' rotator in which the (numerous) low amplitude frequency components can be interpreted not as rotationally-split features but as second- and third-order harmonics and nonlinear combinations of the ten highest amplitude frequencies. This new approach can partly be justified from the observation that the light curve of PG 1605+072 does not resemble any other light curve from short period sdB stars as it shows a highly nonlinear behavior. We present some preliminary results on the basis of this assumption.