Jets from young stars and brown dwarfs

Riaz

Rouze

2018

A&A

Self Cite

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 mag ± 1 mag and the outflow extinction at Av = 9 mag ± 0.4 mag. The H 2 outflow temperature is calculated to be 1422 K ± 255 K and the electron density of the [Fe II] outflow is measured at ∼ 10000 cm −3 . Furthermore, the mass outflow rate is estimated atṀ out[H2] = 3.8 × 10 −10 M yr −1 andṀ out[FeII] = 1 × 10 −8 M yr −1 .Ṁ out[FeII] takes a Fe depletion of ∼ 88% into account. The depletion is investigated using the ratio of the [FeII] 1.257 µm and [PII] 1.188 µm lines. Using the Paβ and Brγ lines and a range in stellar mass and radiusṀ 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.

Section: Outflow Morphology Kinematics and Physical Propertiessupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

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

Riaz

Rouze

2018

A&A

Self Cite

“…young brown dwarfs (0.08 M to 0.13 M ) (e.g., Whelan et al 2005). Although numerous outflows have been detected in the mass range from brown dwarfs to very low mass stars (0.13 M to 0.2 M ), in a majority of the cases, these are micro-jets with projected lengths of ≤0.03 pc (e.g., Whelan 2014). The brown dwarfs or very low-mass stars driving these micro-jets are all optically visible, and are therefore taken to be analogous to Class II YSOs.…”

Section: While Most Of What Is Understood About Outflows Comes From O...mentioning

confidence: 99%

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

Riaz

Heathcote

2017

ApJ

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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.

“…Firstly, this can be done by taking observations using orthogonal slit PAs and combining the offsets measured to estimate a direction and PA for the spatial offsets. This method has been adopted to assign directions and PAs to BD outflows (Whelan 2014;Whelan et al 2012). Secondly, 2D SA can be acheived in a more direct way by analysing integral field spectra (IFS).…”

Section: Spectro-astrometrymentioning

confidence: 99%

Spectro-astrometry of LkCa 15 with X-Shooter: Searching for emission from LkCa 15b

Huélamo

Alcalá

et al. 2015

A&A

Self Cite

Planet formation is one explanation for the partial clearing of dust observed in the disks of some T Tauri stars. Indeed studies using state-of-the-art high angular resolution techniques have very recently begun to observe planetary companions in these so-called transitional disks. The goal of this work is to use spectra of the transitional disk object LkCa 15 obtained with X-Shooter on the Very Large Telescope to investigate the possibility of using spectro-astrometry to detect planetary companions to T Tauri stars. It is argued that an accreting planet should contribute to the total emission of accretion tracers such as Hα and therefore planetary companions could be detected with spectro-astrometry in the same way as it has been used to detect stellar companions to young stars. A probable planetary-mass companion was recently detected in the disk of LkCa 15. Therefore, it is an ideal target for this pilot study. We studied several key accretion lines in the wavelength range 300 nm to 2.2 µm with spectro-astrometry. While no spectro-astrometric signal is measured for any emission lines, the accuracy achieved in the technique is used to place an upper limit on the contribution of the planet to the flux of the Hα, Paγ, and Paβ lines. The derived upper limits on the flux allow an upper limit of the mass accretion rate, log(Ṁ acc ) = −8.9 to −9.3 for the mass of the companion between 6 M Jup and 15 M Jup , respectively, to be estimated (with some assumptions).