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

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 12 CO(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.

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Perseus Protostars. VI. Characterizing the Formation Mechanism for Close Multiple Systems

“…In a similar vein, there have been hypotheses put forward that some clearly detected continuum sources were features produced by outflow interactions (Maury et al 2010(Maury et al , 2012. However, further study over the past several years has found that, the continuum features that were suggested to be outflow knots in VLA 1623, are definitively real protostars Sadavoy et al 2018;Harris et al 2018).…”

ALMA Observations of Polarized 872 μm Dust Emission from the Protostellar Systems VLA 1623 and L1527

“…2 along with a more spatially and kinematically separated Class I component, VLA 1623W, at a distance ∼ 10. 5 and kinematic offset 3 − 4 km/s from the VLA 1623AB subsystem (Bontemps & Andre 1997;Looney et al 2000;Maury et al 2012;Murillo et al 2013). The Keplerian disk in this system orbits the easternmost A component and suggests a component mass of 0.1-0.2 M (Murillo et al 2013).…”

H2O line mapping at high spatial and spectral resolution

“…This has, however, been challenged by the interferometric observations presented in Ward- Thompson et al (2011). An alternative interpretation is that the observed continuum sources close to VLA 1623 are knots in the north-western jet (Maury et al 2012).…”