Shocks and ring in the barred spiral galaxy NGC1530

We present new CO(1–0) and HCN(1–0) observations of the barred spiral galaxy NGC1530 at resolutions of 1.8′′ and 3.6′′ respectively. Both CO and HCN are abundant in the nucleus, where we detect two strong, curved shock fronts curling around a possible nuclear ring. The ring is clumpy and may be elongated along the bar. The kinematics of the gas can be fit with a model with infall motions up to 100 km s−1 along the shocks and quasi-circular rotation in the ring. We estimate the radii of the two inner Lindblad resonances that correspond to the boundaries of the ring and to the location of shock fronts to be 0.1 and 1.2 kpc. Maximum HCN emission seems to arise at the connections of the shock fronts to the nuclear ring, at a radius of 0.6 kpc from the center of the galaxy.