SMA CO(2-1) Observations of CG30: A Protostellar Binary System with a High-Velocity Quadrupolar Molecular Outflow

TL;DR

This study presents high-resolution interferometric observations of a low-mass protostellar binary in CG30, revealing two nearly perpendicular high-velocity bipolar outflows with a quadrupolar morphology, indicating non-coaligned disks post-fragmentation.

Contribution

First detailed interferometric imaging of CG30's binary system showing quadrupolar outflows, highlighting complex disk orientations in binary star formation.

Findings

Resolved two compact sources with distinct masses and separations.

Discovered two high-velocity bipolar outflows with quadrupolar morphology.

Outflow masses differ significantly, with the northern outflow being more massive.

Abstract

We present interferometric observations in the 12CO (2-1) line and at 1.3 mm dust continuum of the low-mass protostellar binary system in the cometary globule CG30, using the Submillimeter Array. The dust continuum images resolve two compact sources (CG30N and CG30S), with a linear separation of ~8700 AU and total gas masses of ~1.4 and ~0.6 M_sun, respectively. With the CO images, we discover two high-velocity bipolar molecular outflows, driven by the two sources. The two outflows are nearly perpendicular to each other, showing a quadrupolar morphology. The northern bipolar outflow extends along the southeast (redshifted, with a velocity up to ~23 km/s) and northwest (blueshifted, velocity up to ~30 km/s) directions, while the southern pair has an orientation from southwest (blueshifted, velocity up to 13 km/s) to northeast (redshifted, velocity up to ~41 km/s). The outflow mass of the northern pair, driven by the higher mass source CG30N, is ~9 times larger than that of the southern pair. The discovery of the quadrupolar molecular outflow in the CG30 protobinary system, as well as the presence of other quadrupolar outflows associated with binary systems, demonstrate that the disks in (wide) binary systems are not necessarily co-aligned after fragmentation.