Subarcsecond SMA observations of the prototype Class 0 object VLA1623 at 1.3 mm: a single protostar with a structured outflow cavity?^⋆

¹ ESO, Karl Schwarzschild Strasse 2, 85748 Garching bei München, Germany
e-mail: amaury@eso.org
² Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, 10617 Taipei, Taiwan
³ Subaru Telescope, National Astronomical Observatory of Japan, Japan
⁴ Laboratoire AIM, CEA/DSM–CNRS–Université Paris Diderot, IRFU/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France

Received: 30 September 2011
Accepted: 18 January 2012

Abstract

We present 1.3-mm subarcsecond SMA observations of the prototypical Class 0 protostar VLA1623. We report the detection of 1.3-mm continuum emission both from the central protostellar component VLA1623 and two additional sources, Knot-A and Knot-B, which have been already detected at longer wavelengths. Knot-A and Knot-B are both located along the western cavity wall opened by the protostellar outflow from VLA1623. Our SMA observations moreover show that these two continuum sources are associated with bright, high-velocity ¹²CO(2–1) emission, slightly shifted downstream of the outflow propagation direction with respect to the 1.3-mm continuum emission peaks. The alignment of Knot-A and Knot-B along the protostellar outflow cavity, the compactness of their 1.3-mm continuum emission, and the properties of the associated CO emission suggest that these two sources trace outflow features due to shocks along the cavity wall, rather than protostellar objects. While it was considered as one of the best examples of a close protobinary system so far, the present analysis suggests that the prototypical Class 0, VLA1623, is single on the scales a > 100 AU probed by our SMA observations. Moreover, we present here the second robust case of compact millimeter continuum emission produced by interactions between the protostellar jet and the envelope of a Class 0 protostar, which suggests a high occurrence of these outflow features during the embedded phase.