Digging into the Interior of Hot Cores with ALMA (DIHCA). VIII. Feeding a high-mass binary system in the making

Abstract

We analyze the gas kinematics in the proto-binary NGC 6334I(N) ALMAe9-ALMAe14 system with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.33 mm with an angular resolution of 66 mas (~90 au). With a separation of 740 au between the system members, these observations allow a detailed study of the gas motion around this likely binary system hosting at least one growing high-mass star. Some CH$_3$OH lines tracing cold gas ($E_u/k_B$~100 K) reveal the presence of ordered circumbinary gas motion around the binary system within a ~1000 au radius, and rotation around the individual sources with rotation axes pointing roughly in the same direction. We estimate a central source mass, uncorrected for inclination, of 2 M$_\odot$ for the secondary, while the primary has an estimated mass of 5 M$_\odot$ as reported in previous works. The CH$_3$OH transitions with higher $E_u/k_B$ ($\gtrsim400$ K) values reveal circumstellar gas rotation in ALMAe9 consistent with the cold gas tracers. The vibrationally excited SO emission also traces rotation around ALMAe9 and potentially an accretion shock from a flow feeding the circumstellar disk of ALMAe14. We identify two potential inflows feeding the circumstellar disks from the circumbinary gas at rates of ~$10^{-6}-10^{-4}$ M$_\odot$ yr$^{-1}$ from CH$_3$OH emission. An additional third inflow seems to be feeding the primary from gas at larger scales.