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

摘要

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 H_(2)and [Fe II] lines at V _(sys)= (–35 ± 2) km s~(?1)and V _(sys)= (–51 ± 5) km s~(?1)respectively. In addition, slower (~±10 km s~(?1)) H_(2)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 H_(2)emission is tracing a cavity. The source extinction is estimated at A _( v )= 18 ± 1 mag and the outflow extinction at A _( v )= 9 ± 0.4 mag. The H_(2)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? ? _(out [H_(2)])? = 3.8 × 10~(?10) M _(⊙)yr~(?1)and? ? _(out[Fe II])= 1 × 10~(?8) M _(⊙)yr~(?1).? ? _(out[Fe II])takes a Fe depletion of ~88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μ m and [P II] 1.188 μ m lines. Using the Pa β and Br γ lines and a range in stellar mass and radius ? _(acc)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.