First Large-scale Herbig–Haro Jet Driven by a Proto-brown Dwarf

Abstract

We report the discovery of a new Herbig-Haro jet, HH 1165, in SOAR narrowband imaging of the vicinity of the σ Orionis cluster. HH 1165 shows a spectacular extended and collimated spatial structure, with a projected length of 0.26 pc, a bent C-shaped morphology, multiple knots, and fragmented bow-shocks at the apparent ends of the flow. The Hα image shows a bright halo with a clumpy distribution of material seen around the driving source, and curved reflection nebulosity tracing the outflow cavities. The driving source of HH 1165 is a Class I proto-brown dwarf, Mayrit 1701117 (M1701117), with a total (dust+gas) mass of ∼36 M Jup and a bolometric luminosity of ∼0.1 L . High-resolution VLT/UVES spectra of M1701117 show a wealth of emission lines indicative of strong outflow and accretion activity. SOAR/Goodman low-resolution spectra along the jet axis show an asymmetrical morphology for HH 1165. We find a puzzling picture wherein the north-west part exhibits a classical HH jet running into a pre-dominantly neutral medium, while the southern part resembles an externally irradiated jet. The C-shaped bending in HH 1165 may be produced by the combined effects from the massive stars in the ionization front to the east, the σ Orionis core to the west, and the close proximity to the B2-type star HR 1950. HH 1165 shows all of the signatures to be considered as a scaled-down version of parsec-length HH jets, and can be termed as the first sub-stellar analog of a protostellar HH jet system.

ALMA reveals a pseudo-disc in a proto-brown dwarf

“…There is a good match between the CC model and observations for the brighter red-shifted lobe, whereas the blue lobe is shifted by ∼1 km s −1 and slightly towards the south-west than predicted by the model. The deflection in the blue lobe appears similar to that seen in the southern part of the HH 1165 jet close to the driving source (Riaz et al 2017), and is possibly caused by the wind-outflow collision (Sect. 5).…”

“…A comparison of the observed velocity spread with various models (Sect. 4.2.1) also suggests this system to be more evolved than the dynamical age of the jet (∼2900 yr; Riaz et al 2017). This object is located in an irradiated environment (Riaz et al 2017), which could further expedite the dissipation of the circumstellar material.…”

“…4.2.1) also suggests this system to be more evolved than the dynamical age of the jet (∼2900 yr; Riaz et al 2017). This object is located in an irradiated environment (Riaz et al 2017), which could further expedite the dissipation of the circumstellar material. Considering these scenarios, M1701117 is likely to reach a final mass below the sub-stellar limit and become a brown dwarf.…”

“…40,000 yr. The proto-brown dwarf is therefore not as young as the dynamical age of the HH 1165 jet (∼2900 yr; Riaz et al 2017), but has reached the protostellar phase (∼0.01-0.1 Myr; e.g., Evans et al 2009). As already noted in Sect.…”

A diagnostic tool for the identification of supernova remnants

“…On the other hand although Herbig-Haro objects are excited by the shock of the jets of young stellar objects, their total luminosity (∼ 0.1L ; e.g. Riaz et al 2017) renders them unobservable in SNR surveys of nearby galaxies. In our Galaxy they can be easily discriminated from SNRs on the basis of their morphology.…”