Geometric differences between the gaseous and stellar warps in the Milky Way

Careful modelling of the stellar and gaseous distributions in the Milky Way disc has been carried out in order to study the stellar warp. We have analysed the observations in the near infrared made by the ”Diffuse Infrared Background Experiment” (DIRBE) on board COBE as reported by Freudenreich et al. (1994). These authors found a dependence of the displacement of the maximum emission on galactic longitude, which is however less than that observed at 21 cm. Our model enables us to reject the interpretation of this displacement as being due to the fact that the Sun does not exactly lie in the galactic plane. Either the stellar disc is large but is less warped than the gaseous disc, or it has a cutoff at r ∼ 15 kpc. Preliminary results from DENIS (Ruphy et al. 1996) indicate a cutoff at 15 kpc, favouring the latter interpretation.