The first ALMA view of IRAS 16293-2422^⋆,⋆⋆

Direct detection of infall onto source B and high-resolution kinematics of source A

¹ European Southern Observatory (ESO), Garching, Germany
e-mail: jaime.pineda@manchester.ac.uk
² UK ARC Node, Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
³ INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁴ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
⁵ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
⁶ North American ALMA Science Center, National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
⁷ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁸ Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095, USA
⁹ National Astronomical Observatory of Japan, Chile Observatory, 2-21-1 Osawa Mitaka, 181-8588 Tokyo, Japan

Received: 12 May 2012
Accepted: 22 June 2012

Abstract

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.