Locating the Launching Region of T Tauri Winds: The Case of DG Tauri

Anderson, Jeffrey M.; Li, Zhi-Yun; Krasnopolsky, Ruben; Blandford, R. D.

doi:10.1086/376824

Cited by 196 publications

(278 citation statements)

References 16 publications

(27 reference statements)

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“…Furthermore, the slowest jet material at V r 30−60 km s −1 exhibits velocity shifts between the two sides of the jet (Bacciotti et al 2000;Coffey et al 2007) in the same sense as the rotation of the DG Tau disk (Testi et al 2002). These transverse shifts excellently agree with predicted rotation signatures for a steady-state MHD disk wind launched out to about 3 AU (Anderson et al 2003;Pesenti et al 2004;Ferreira et al 2006). A velocity shift in the same sense is seen across faster jet material at −200 km s −1 suggesting (if caused by rotation) ejection from smaller disk radii of 0.2−0.5 AU (Coffey et al 2007).…”

Section: Introductionsupporting

confidence: 72%

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Agra-Amboage

Dougados

Cabrit

et al. 2011

A&A

111

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Context. The origin of protostellar jets as well as their impact on the regulation of angular momentum and the inner disk physics are still crucial open questions in star formation. Aims. We aim to test the different proposed ejection processes in T Tauri stars through high-angular resolution observations of forbidden-line emission from the inner DG Tauri microjet. Methods. We present spectro-imaging observations of the DG Tauri jet obtained with SINFONI/VLT in the lines of [Fe ii]λ1.64 μm, 1.53 μm with 0. 15 angular resolution and R = 3000 spectral resolution. We analyze the morphology and kinematics, derive electronic densities and mass-flux rates and discuss the implications for proposed jet launching models. Results. (1) We observe an onion-like velocity structure in [Fe ii] in the blueshifted jet, similar to that observed in optical lines. Highvelocity (HV) gas at -200 km s −1 is collimated inside a half-opening angle of 4 • and medium-velocity (MV) gas at -100 km s −1 in a cone with an half-opening angle 14.• (2) Two new axial jet knots are detected in the blue jet, as well as a more distant bubble with corresponding counter-bubble. The periodic knot ejection timescale is revised downward to 2.5 yrs. (3) The redshifted jet is detected only beyond 0. 7 from the star, yielding revised constraints on the disk surface density. (4) From comparison to [O i] data we infer iron depletion of a factor 3 at high velocities and a factor 10 at speeds below -100 km s −1 . (5) The mass-fluxes in each of the medium and high-velocity components of the blueshifted lobe are 1.6 ± 0.8 × 10 −8 M yr −1 , representing 0.02−0.2 of the disk accretion rate. Conclusions. The medium-velocity conical [Fe ii] flow in the DG Tau jet is too fast and too narrow to trace photo-evaporated matter from the disk atmosphere. Both its kinematics and collimation cannot be reproduced by the X-wind, nor can the "conical magnetospheric wind". The level of Fe gas phase depletion in the DG Tau medium-velocity component also rules out a stellar wind and a cocoon ejected sideways from the high-velocity beam. A quasi-steady centrifugal MHD disk wind ejected over 0.25−1.5 AU and/or episodic magnetic tower cavities launched from the disk appear as the most plausible origins for the [Fe ii] medium velocity component in the DG Tau jet. The same disk wind model can also account for the properties of the high-velocity [Fe ii] flow, although alternative origins in magnetospheric and/or stellar winds cannot be excluded for this component.

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Section: Introductionsupporting

confidence: 72%

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Agra-Amboage

Dougados

Cabrit

et al. 2011

A&A

111

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“…Microjets are hardly resolved transversely. Thus, this speed might be a mixing of the high-and low-velocity components similarly to what is observed in DG Tau (Anderson et al 2003). For the highvelocity component we can easily take a higher value and assume 400 km s −1 along the polar axis, where we expect to find this maximum value.…”

Section: Jet Constraintsmentioning

confidence: 74%

Nonradial and nonpolytropic astrophysical outflows

Sauty

Méliani

Lima

et al. 2011

A&A

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Context. A large sample of T Tauri stars exhibits optical jets, approximately half of which rotate slowly, only at ten per cent of their breakup velocity. The disk-locking mechanism has been shown to be inefficient to explain this observational fact. Aims. We show that low mass accreting T Tauri stars may have a strong stellar jet component that can effectively brake the star to the observed rotation speed. Methods. By means of a nonlinear separation of the variables in the full set of the MHD equations we construct semi-analytical solutions describing the dynamics and topology of the stellar component of the jet that emerges from the corona of the star. Results. We analyze two typical solutions with the same mass loss rate but different magnetic lever arms and jet radii. The first solution with a long lever arm and a wide jet radius effectively brakes the star and can be applied to the visible jets of T Tauri stars such as RY Tau. The second solution with a shorter lever arm and a very narrow jet radius may explain why similar stars, either weak line T Tauri stars (WTTS) or classical T Tauri stars (CTTS) do not all have visible jets. For instance, RY Tau itself seems to have different phases that probably depend on the activity of the star. Conclusions. First, stellar jets seem to be able to brake pre-main sequence stars with a low mass accreting rate. Second, jets may be visible only part time owing to changes in their boundary conditions. We also suggest a possible scenario for explaining the dichotomy between CTTS and WTTS, which rotate faster and do not have visible jets.

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“…The LVC centroids in optical forbidden lines are known to display clear asymmetries between opposite sides of the jet axis, with amplitude and sign consistent with a rotating, steady magneto-centrifugal disc wind launched out to 3 AU Anderson et al 2003;Pesenti et al 2004;Coffey et al 2007, cf. Fig.…”

Section: Constraints On H 2 Rotationmentioning

confidence: 94%

Origin of the wide-angle hot H₂in DG Tauri

Agra-Amboage

Cabrit

Dougados

et al. 2014

A&A

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Context. The origin of protostellar jets remains a major open question in star formation. Magnetohydrodynamical (MHD) disc winds are an important mechanism to consider, because they would have a significant impact on planet formation and migration. Aims. We wish to test the origins proposed for the extended hot H 2 at 2000 K around the atomic jet from the T Tauri star DG Tau, in order to constrain the wide-angle wind structure and the possible presence of an MHD disc wind in this prototypical source. Methods. We present spectro-imaging observations of the DG Tau jet in H 2 1-0 S(1) with 0. 12 angular resolution, obtained with SINFONI/VLT. Thanks to spatial deconvolution by the point spread function and to careful correction for wavelength calibration and for uneven slit illumination (to within a few km s −1 ), we performed a thorough analysis and modeled the morphology and kinematics. We also compared our results with studies in [Fe II], [O I], and FUV-pumped H 2 . Absolute flux calibration yields the H 2 column/volume density and emission surface, and narrows down possible shock conditions. Results. The limb-brightened H 2 1-0 S(1) emission in the blue lobe is strikingly similar to FUV-pumped H 2 imaged 6 yr later, confirming that they trace the same hot gas and setting an upper limit <12 km s −1 on any expansion proper motion. The wide-angle rims are at lower blueshifts (between -5 and 0 km s −1 ) than probed by narrow long-slit spectra. We confirm that they extend to larger angle and to lower speed the onion-like velocity structure observed in optical atomic lines. The latter is shown to be steady over ≥4 yr but undetected in [Fe II] by SINFONI, probably due to strong iron depletion. The rim thickness ≤14 AU rules out excitation by C-type shocks, and J-type shock speeds are constrained to 10 km s −1 . Conclusions. We find that explaining the H 2 1-0 S(1) wide-angle emission with a shocked layer requires either a recent outburst (15 yr) into a pre-existing ambient outflow or an excessive wind mass flux. A slow photoevaporative wind from the dense irradiated disc surface and an MHD disc wind heated by ambipolar diffusion seem to be more promising and need to be modeled in more detail. Better observational constraints on proper motion and rim thickness would also be crucial for clarifying the origin of this structure.

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Locating the Launching Region of T Tauri Winds: The Case of DG Tauri

Cited by 196 publications

References 16 publications

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Nonradial and nonpolytropic astrophysical outflows

Origin of the wide-angle hot H₂in DG Tauri

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Locating the Launching Region of T Tauri Winds: The Case of DG Tauri

Cited by 196 publications

References 16 publications

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Sub-arcsecond [Fe ii] spectro-imaging of the DG Tauri jet

Nonradial and nonpolytropic astrophysical outflows

Origin of the wide-angle hot H2in DG Tauri

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Origin of the wide-angle hot H₂in DG Tauri