The first ALMA view of IRAS 16293-2422

Aims. We focus on the kinematical properties of a proto-binary to study the infall and rotation of gas toward its two protostellar components. Methods. We present ALMA Science Verification observations with high-spectral resolution of IRAS 16293-2422 at 220.2 GHz. The wealth of molecular lines in this source and the very high spectral resolution offered by ALMA allow us to study the gas kinematics with unprecedented detail. Results. We present the first detection of an inverse P-Cygni profile toward source B in the three brightest lines. The line profiles are fitted with a simple two-layer model to derive an infall rate of 4.5 × 10-5 M⊙ yr-1. This infall detection would rule-out the previously suggested possibility that source B is a T Tauri star. A position velocity diagram for source A shows evidence of rotation with an axis close to the line-of-sight