Mass distribution and kinematics of the barred galaxy NGC2336

Abstract

For the intermediate-type barred galaxy NGC2336 stationary models are constructed which reproduce in a consistent manner the observed distribution of the luminous matter and the observed gas kinematics in those regions affected by the bar. We present 2D fits to the observed NIR-band luminosity distribution that consist of three components: a bulge, a bar, and a disk. The brightness distribution of each component is converted into an underlying mass distribution by means of a suitable M/L-conversion. The resulting coadded potential of NGC2336 is implemented into a numerical code for the computation of closed orbits for gas clouds (HII-gas). Using the resulting tracks, the phase space accessible to the models is examined with regard to the main orbit families. For different orbit energies complete sets of closed orbits are computed. By projection to the reference frame of the galaxy, artificial rotation curves for every model are obtained and are compared with the observed rotation curves of the HII-gas. In an iterative procedure, the parameters of the NGC2336-models are optimized by computing and evaluating a large number of parameters. The result is a final model that reproduces the morphological structure of NGC2336 as well as the observed kinematics of the HII-gas. The parameter values from the morphological decomposition and those needed to fit the HII-rotation curves best are in exellent agreement. The effects of changing single parameter values and possible error sources are discussed in detail. It turns out that the kinematics of the warm HII-gas of NGC2336 can be explained without considering hydrodynamic effects, even in the central regions.