The First Proto-Brown Dwarf Binary Candidate Identified through Dynamics of Jets

Abstract

The formation mechanism of brown dwarfs (BDs) is one of the long-standing problems in star formation because the typical Jeans mass in molecular clouds is too large to form these substellar objects. To answer this question, it is crucial to study a BD at the embedded phase (proto-brown dwarf). IRAS16253 is classified as a Very Low Luminosity Object (VeLLO, L_int < 0.1L_⊙), which is considered as a proto-brown dwarf candidate. We use the IRAM 30m, APEX telescopes and the SMA to probe the molecular jet/outflow driven by IRAS 16253 in CO (2–1), (6–5), and (7–6) and study its dynamical features and physical properties. We detect a wiggling pattern in the position-velocity diagrams of the jets. Assuming that this pattern is due to the orbital motion of a binary system, we obtain the current mass of the binary is ~0.026 M_⊙. Together with the low parent core mass, IRAS16253 will likely form one or two proto-BD in the future. This is the first time that the current mass of a proto-BD binary system is identified through the dynamics of the jets. Since IRAS16253 is located in an isolated environment, we suggest that BDs can form through fragmentation and collapse like low mass stars.