First results from the CALYPSO IRAM-PdBI survey

I. Kinematics of the inner envelope of NGC 1333-IRAS2A^{⋆,⋆⋆,⋆⋆⋆}

¹ UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble, UMR 5274, 38041 Grenoble, France
e-mail: sebastien.maret@obs.ujf-grenoble.fr
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
³ Harvard-Smithsonian Center for Astrophysics, 60 Garden street, Cambridge MA 02138, USA
⁴ IRAM, 300 rue de la piscine, 38406 Saint Martin d’Hères, France
⁵ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Université Paris Diderot, CE-Saclay, 91191 Gif-sur-Yvette, France
⁶ LERMA, Observatoire de Paris, CNRS, ENS, UPMC, UCP, 61 Av de l’Observatoire, 75014 Paris, France
⁷ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁸ Université de Bordeaux, LAB, UMR 5804, 33270 Floirac, France
⁹ CNRS, LAB, UMR 5804, 33270 Floirac, France

Received: 11 November 2013
Accepted: 22 January 2014

Abstract

The structure and kinematics of Class 0 protostars on scales of a few hundred AU is poorly known. Recent observations have revealed the presence of Keplerian disks with a diameter of 150–180 AU in L1527-IRS and VLA1623A, but it is not clear if such disks are common in Class 0 protostars. Here we present high-angular-resolution observations of two methanol lines in NGC1333-IRAS2A. We argue that these lines probe the inner envelope, and we use them to study the kinematics of this region. Our observations suggest the presence of a marginal velocity gradient normal to the direction of the outflow. However, the position velocity diagrams along the gradient direction appear inconsistent with a Keplerian disk. Instead, we suggest that the emission originates from the infalling and perhaps slowly rotating envelope, around a central protostar of 0.1−0.2  M_⊙. If a disk is present, it is smaller than the disk of L1527-IRS, perhaps suggesting that NGC 1333-IRAS2A is younger.