Sub-arcsecond SMA observations of the prototype Class 0 object VLA1623 at 1.3 mm: A single protostar with a structured outflow cavity ?

TL;DR

This study uses subarcsecond SMA observations at 1.3 mm to investigate the prototypical Class 0 protostar VLA1623, revealing it as a single protostar with outflow-related features rather than a binary system.

Contribution

The paper provides high-resolution observations showing VLA1623 is single and identifies shock-related outflow features as common in early protostellar stages.

Findings

VLA1623 is a single protostar, not a binary.

Knot-A and Knot-B are outflow shock features, not protostars.

Outflow-envelope interactions are common in Class 0 protostars.

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.