1999A&A...348..685G

We have mapped the emission from atomic hydrogen at λ=21cm from the galaxy NGC 3783 with the Australia Telescope Compact Array. Our main results are: a) the HI morphology is irregular and perturbed, gathered in three blobs apparently unrelated to the optical morphology; b) the observed HI velocity distribution indicates a normal disk in differential rotation with a constant velocity out to a radius of 160" (30kpc), c) the inclination of the disk is about 25° with the kinematic major axis at a position angle slightly different from that of the stellar bar, d) the HI mass inside a radius of 18" is only 2.1x10⁷M_☉, the total HI mass within 180" is 1.1x10⁹M_☉ and the dynamical mass is 2x10¹¹M_☉. The bulk of the gas in NGC 3783 is outside the diameter of the stellar bar; e) Numerical simulations of the gas flow in the barred potential derived from the red image indicate that the pattern speed is Ω_p=38km/s/kpc: the ring of Hα emitting regions encircling the bar would then correspond to UHR, and the Hα accumulation in the center to a nuclear ring. Various possibilities are discussed to account for the active nucleus fuelling.