IRAM,04191+1522: A compact proto-brown dwarf binary candidate

Very low luminosity objects (VeLLOs) in nearby star-forming regions have been identified as promising proto-brown dwarf candidates, and studying their multiplicity can shed light on the dominant formation mechanism of substellar objects. Our aim is to study the multiplicity of the VeLLO IRAM,04191+1522. We obtained 0.89,mm ALMA observations with a very extended configuration that achieved an angular resolution of ∼0farcs04 (6,au at 140,pc). We complemented these data with new VLA observations and ALMA archival data at 1.3,mm. We resolved IRAM04191+1522 into a close binary candidate for the first time. The binary is detected in the ALMA continuum data with a projected separation of ∼80,mas (or 11,au at a distance of 140,pc). The two sources are oriented in the east-west direction, with the eastern component being brighter and more extended than the western one, which is marginally resolved. Analysis of ̧eo(2-1) archival data revealed gaseous material in rotation around the binary, presumably from a circumbinary disk with ∼27,au of radius centered on the faintest ALMA component. A fit of the position-velocity diagram allowed us to estimate a total dynamical mass for the system of 50±40, Therefore, we classify IRAM04191 as a tight proto-brown dwarf binary candidate. The VLA data revealed the detection of a single object closer to the western ALMA source with a spectral index consistent with a radio jet.