Early Planet Formation in Embedded Disks. XI. A High-resolution View Toward the BHR 71 Class 0 Protostellar Wide Binary

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the binary Class 0 protostellar system BHR 71 IRS1 and IRS2 as part of the Early Planet Formation in Embedded Disks (eDisk) ALMA Large Program. We describe the ^12 CO ( J = 2–1), ^13 CO ( J = 2–1), C ^18 O ( J = 2–1), H _2 CO ( J = 3 _2,1 –2 _2,0 ), and SiO ( J = 5–4) molecular lines along with the 1.3 mm continuum at high spatial resolution (∼0.″08 or ∼5 au). Dust continuum emission is detected toward BHR 71 IRS1 and IRS2, with a central compact component and extended continuum emission. The compact components are smooth and show no sign of substructures such as spirals, rings, or gaps. However, there is a brightness asymmetry along the minor axis of the presumed disk in IRS1, possibly indicative of an inclined geometrically and optically thick disk-like component. Using a position–velocity diagram analysis of the C ^18 O line, clear Keplerian motions were not detected toward either source. If Keplerian rotationally supported disks are present, they are likely deeply embedded in their envelope. However, we can set upper limits of the central protostellar mass of 0.46 M _⊙ and 0.26 M _⊙ for BHR 71 IRS1 and BHR 71 IRS2, respectively. Outflows traced by ^12 CO and SiO are detected in both sources. The outflows can be divided into two components, a wide-angle outflow and a jet. In IRS1, the jet exhibits a double helical structure, reflecting the removal of angular momentum from the system. In IRS2, the jet is very collimated and shows a chain of knots, suggesting episodic accretion events.

Keywords

• Star formation
• Circumstellar disks
• Stellar jets