Spatially resolved H₂emission from a very low-mass star

Abstract

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 H 2 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 H 2 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 H 2 transitions, we are able to estimate average values along the jet-like structure (from source position to knot D) of A V ∼ 28 mag, T ∼ 2000−3000 K, and H 2 column density N(H 2 ) ∼ 1.7 × 10 17 cm −2 . This allows us to estimate a mass loss rate of ∼2 × 10 −10 M yr −1 for the warm H 2 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 −7 M yr −1 , 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.

Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits

“…Extended H 2 emission is commonly observed in the form of both bipolar jets and isolated outflows from young stars. NIR IFU observations in particular enable detailed spatial and kinematic studies of molecular hydrogen outflows (e.g., Beck et al 2008;Davis et al 2011;García López et al 2013). To check for extended structure, we registered and coadded our nodded OSIRIS cubes for each emission line seen in our 2011 and 2013 data, subtracted continuum images adjacent to each line, and fit a 2D elliptical Gaussian to the source.…”

INVESTIGATING 2MASS J06593158-0405277: AN FUor BURST IN A TRIPLE SYSTEM?

“…Additionally, continuum images (at 1.25 and 2.2 μm) and continuum-subtracted Paβ and Brγ images were created following the same procedures as in Beck et al (2008) and Garcia Lopez et al (2013).…”