2013A&A...552L...2G

Molecular outflows from very low-mass stars (VLMSs) and brown dwarfs have been studied very little. So far, only a few CO outflows have been observed, allowing us to map the immediate circumstellar environment. We present the first spatially resolved H₂ emission around IRS54 (YLW52), a ∼0.1-0.2M_☉ Class I source. By means of VLT SINFONI K-band observations, we probed the H₂ emission down to the first ∼50AU from the source. The molecular emission shows a complex structure delineating a large outflow cavity and an asymmetric molecular jet. Thanks to the detection of several H₂ transitions, we are able to estimate average values along the jet-like structure (from source position to knot D) of A_V∼28mag, T∼2000-3000K, and H₂ column density N(H₂)∼1.7x10¹⁷cm^–2. This allows us to estimate a mass loss rate of ∼2x10^–10M_☉/yr for the warm H₂ component. In addition, from the total flux of the Brγ line, we infer an accretion luminosity and mass accretion rate of 0.64L_☉ and ∼3x10^–7M_☉/yr, respectively. The outflow structure is similar to those found in low-mass Class I and CTTS. However, the L_acc/L_bol ratio is very high (∼80%), and the mass accretion rate is about one order of magnitude higher when compared to objects of roughly the same mass, pointing to the young nature of the investigated source.