Max – Planck – Institut für Radioastronomie,
Auf dem Hügel 69,
2 INAF – Osservatorio Astronomico di Roma via Frascati 33, 00040 Monteporzio Catone, Italy
Received: 15 January 2013
Accepted: 23 February 2013
Context. 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.
Aims. We present the first spatially resolved H2 emission around IRS54 (YLW 52), a ~0.1–0.2 M⊙ Class I source.
Methods. By means of VLT SINFONI K-band observations, we probed the H2 emission down to the first ~50 AU from the source.
Results. 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 AV ~ 28 mag, T ~ 2000−3000 K, and H2 column density N(H2) ~ 1.7 × 1017 cm-2. This allows us to estimate a mass loss rate of ~2 × 10-10 M⊙ yr-1 for the warm H2 component. In addition, from the total flux of the Br γ line, we infer an accretion luminosity and mass accretion rate of 0.64 L⊙ and ~3 × 10-7M⊙ yr-1, respectively. The outflow structure is similar to those found in low-mass Class I and CTTS. However, the Lacc/Lbol 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.
Key words: stars: formation / circumstellar matter / stars: winds, outflows / ISM: jets and outflows / infrared: ISM
Based on observations collected at the European Southern Observatory Paranal, Chile (ESO programme 385.C-0893(A)).
Appendices are available in electronic form at http://www.aanda.org
The reduced datacube is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/552/L2
© ESO, 2013