Molecular Gas and the Nuclear Star Cluster in IC342: Sufficient Inflow for Recurring Star Formation Events?

We present high spatial resolution (1.2′′) mm-interferometric observations of the 12CO(2− 1) line emission in the central 300 pc of the late-type spiral galaxy IC 342. The data, obtained with the Owens Valley Radio Observatory, allow firsttime detection of a molecular gas disk that coincides with the luminous young stellar cluster in the nucleus of IC 342. The nuclear CO disk has a diameter of ∼ 30pc and a molecular gas mass of MH2 ∼ 2×105 M . It connects via two faint CO bridges to the well-known, 100 pc diameter circumnuclear gas ring. Analysis of the gas kinematics shows that the line-of-nodes in the inner 15 pc is offset by about 45◦ from the major kinematic axis, indicating non-circular motion of the gas within a few parsec of the dynamical center of IC 342. Both the morphology and the kinematics of the CO gas indicate ongoing inflow of molecular gas into the central few parsec of IC 342. We infer a gas inflow rate between 0.003 and 0.14 M yr−1, based on the observed surface density of the nuclear gas disk and estimates of the radial velocities of the surrounding gas. Inflow rates of this order can support repetitive star formation events in the nucleus of IC 342 on timescales much smaller than a Hubble time. Subject headings: galaxies: nuclei — galaxies: ISM — galaxies: kinematics and dynamics — galaxies: individual(IC 342)