A gas-rich nuclear bar fueling a powerful central starburst in NGC 2782

We present evidence that the peculiar interacting starburst galaxy NGC 2782 (Arp 215) harbors a gas-rich nuclear stellar bar feeding an M82-class powe rful central starburst, from a study based on high-resolution interferometr ic CO (J = 1 --> 0) data and optical BVR and H alpha observations, along wi th available near-infrared (NIR) images, a 5 GHz radio continuum map, and a rchival Hubble Space Telescope (HST) images. Morphological and kinematic da ta show that NGC 2782 harbors a clumpy, barlike CO feature of radius simila r to 7".5 (1.3 kpc) that leads a nuclear stellar bar of similar size. The n uclear barlike CO feature is massive: it contains similar to 2.5 x 10(9) M- circle dot of molecular gas, which makes up similar to 8% of the dynamical mass present within a 1.3 kpc radius. Within the CO bar, emission peaks in two extended clumpy lobes that lie on opposite sides of the nucleus, separa ted by similar to 6" (1 kpc). Between the CO lobes, in the inner 200 pc rad ius, resides a powerful central starburst that is forming stars at a rate o f 3-6 M-circle dot yr(-1). While circular motions dominate the CO velocity field, the CO lobes show weak barlike streaming motions on the leading side of the nuclear stellar bar, suggestive of gas inflow. We estimate semianal ytically the gravitational torque from the nuclear stellar bar on the gas a nd suggest large gas inflow rates from the CO lobes into the central starbu rst. These observations, which are among the first ones showing a nuclear s tellar bar fueling molecular gas into an intense central starburst, are con sistent with simulations and theory, which suggest that nuclear bars provid e an efficient way of transporting gas closer to the galactic center to fue l central activity. Furthermore, several massive (10(7)-10(8) M-circle dot) clumps are present at low radii, and dynamical friction might produce furt her gas inflow. We suggest that the nuclear barlike molecular gas feature a nd central activity will be very short lived, likely disappearing within 5 x 10(8) yr.