Kinematical models of warped disks

A new approach to study the morphology and kinematics of gaseous structures is presented, using a model where warped and twisted planes are simulated in the three dimensions, with gas moving in circular orbits. The kinematics and morphology of this gas are projected on the plane of the sky and compared with real images and long-slit spectral data. Due to its simplicity, this method is very versatile and can be applied to many different cases of warped gas structures: polar rings, tumbling potentials, and acquired gas settling to the main galaxy plane. It can be used in two different ways: as an heuristic approach to give a better estimation for the rotation curves, starting from the observational data (images and velocity) or to check the predictions of warped and twisted gas structure computed using - N-body simulations or dynamical - codes. The mathematical details of the model are discussed. Model results are compared to three galaxies: the model of NGC 660 is discussed in some details and those for the warped structure of the SB0 NGC 2217 and the polar ring galaxy AM 2020-504 are briefly presented.