The near-infrared outflow and cavity of the proto-brown dwarf candidate ISO-Oph 200

Abstract

In this Letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A ~0.′′5 blue-shifted outflow is detected in both H2 and [Fe II] lines at Vsys = (–35 ± 2) km s−1 and Vsys = (–51 ± 5) km s−1 respectively. In addition, slower (~±10 km s−1) H2 emission is detected out to <5.′′4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H2 emission is tracing a cavity. The source extinction is estimated at Av = 18 ± 1 mag and the outflow extinction at Av = 9 ± 0.4 mag. The H2 outflow temperature is calculated to be 1422 ± 255 K and the electron density of the [Fe II] outflow is measured at ~10 000 cm−3. Furthermore, the mass outflow rate is estimated at Ṁout [H2]  = 3.8 × 10−10 M⊙ yr−1 and Ṁout[Fe II] = 1 × 10−8 M⊙ yr−1. Ṁout[Fe II] takes a Fe depletion of ~88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μm and [P II] 1.188 μm lines. Using the Paβ and Brγ lines and a range in stellar mass and radius Ṁacc is calculated to be (3–10) × 10−8 M⊙ yr−1. Comparing these rates puts the jet efficiency in line with predictions of magneto-centrifugal models of jet launching in low mass protostars. This is a further case of a brown dwarf outflow exhibiting analogous properties to protostellar jets.