<i>Hubble Space Telescope</i>Space Telescope Imaging Spectrograph Observations of the Bipolar Jet from RW Aurigae: Tracing Outflow Asymmetries Close to the Source

Woitas, J.; Ray, T. P.; Bacciotti, F.; Davis, C. J.; Eislöffel, J.

doi:10.1086/343124

Cited by 132 publications

(190 citation statements)

References 27 publications

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“…3 our derived intrinsic jet radii in [Fe ii] with previous measurements from velocity-integrated [O i] images at similar angular resolution in the RW Aur jet (average of both lobes) (Woitas et al 2002) and in the HN Tau and UZ Tau E blueshifted jets (Hartigan et al 2004a). The RW Aur microjet, where [O i] is dominated by a single highvelocity component (Woitas et al 2002), shows an opening angle and width strikingly similar to the HVB interval in DG Tau. The HN Tau and UZ Tau E [O i] jets, dominated by a medium to low-velocity component (Hartigan et al 1995), have a much wider opening angle similar to the MVB.…”

Section: Collimation Opening Angle and Upper Limits On Launch Radiisupporting

confidence: 80%

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: Collimation Opening Angle and Upper Limits On Launch Radiisupporting

confidence: 80%

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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“…Stellar jet asymmetry is observed in a increasing number of systems as the ejection velocities of the jet and counterjet differ by about a factor of 2 (Hirth et al 1994;Woitas et al 2002;López-Martín et al 2003;Lavalley et al 1997;Fernández and Comerón 2005;Watson and Stapelfeldt 2007;Garcia Lopez et al 2010Melnikov et al 2009;Podio et al 2011;. Jet launching regions (JLRs) are confined to the inner part of the disk with estimates from 0.01 AU for the X-wind model to a few AU for disk-wind models (e.g.…”

Section: Orbital Excitation By Asymmetric Jet Momentum Lossmentioning

confidence: 99%

The excitation of planetary orbits by stellar jet variability and polarity reversal

Namouni

2012

Astrophys Space Sci

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Planets form in active protoplanetary disks that sustain stellar jets. Momentum loss from the jet system may excite the planets' orbital eccentricity and inclination (Namouni 2005, AJ 130, 280). Evaluating quantitatively the effects of such excitation requires a realistic modeling of the momentum loss profiles associated with stellar jets. In this work, we model linear momentum loss as a time-variable stochastic process that results in a zero mean stellar acceleration. Momentum loss may involve periodic or random polarity reversals. We characterize orbital excitation as a function of the variability timescale and identify a novel excitation resonance between a planet's orbital period and the jet's variability timescale where the former equals twice the latter. For constant variability timescales, resonance is efficient for both periodic and random polarity reversals, the latter being stronger than the former. For a time variable variability timescale, resonance crossing is a more efficient excitation mechanism when polarity reversals are periodic. Each polarity reversal type has distinct features that may help constrain the magnetic history of the star through the observation of its planetary companions. For instance, outward planet migration to large distances from parent stars is one of the natural outcomes of periodic polarity reversal excitation if resonance crossing is sufficiently slow. Applying the excitation mechanism to the solar system, we find that the planet-jet variability resonance with periodic polarity reversal momentum loss is a possible origin for the hitherto unexplained inclination of Jupiter's orbit by 6 • with respect to the Sun's equator.

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“…The application of these methods to analyse emission lines allows one to derive the jet structure on different scales, depending on the angular resolution of the observations: from parsec scales to hundreds of AU (Hartigan et al 1994;Podio et al 2006), and down to ∼15 AU from the emitting source with space or adaptive optics-assisted observations (Bacciotti et al 2000;Lavalley-Fouquet et al 2000;Woitas et al 2002;Hartigan & Morse 2007;Melnikov et al 2009). In particular, the analysis of emission lines can shed light on the gas conditions at the base of the flow and on the mechanism that generates this flow.…”

Section: Introductionmentioning

confidence: 99%

“…Despite some attempts to explain these observational features by means of the existing MHD models (e.g., Pesenti et al 2003;Ferreira et al 2006), their origin is still unclear. A viable possibility to clarify these aspects is to investigate the variation of the jet physical properties in asymmetric jets and in different velocity channels, which has been attempted in recent works conducted at moderate and high spatial/spectral resolution (Lavalley-Fouquet et al 2000;Woitas et al 2002;Coffey et al 2008;Garcia Lopez et al 2008Melnikov et al 2009;Podio et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Tracing kinematical and physical asymmetries in the jet from DG Tauri B

Podio¹,

Eislöffel

Melnikov

et al. 2011

A&A

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Context. Jets from young stars can be highly asymmetric and have multiple velocity components. Aims. To clarify the origin of jet asymmetries and constrain the launch mechanism, we study as a test case the physical and kinematical structure of the prototypical asymmetric flow emitted by DG Tau B. Methods. The analysis of deep, high spectral resolution observations taken with the KECK telescope allows us to infer the properties and the spatial distribution of the velocity components in the two jet lobes. From selected line ratios we derive the gas physical conditions (the electron and total density, n e and n H , the ionisation fraction, x e , and the temperature, T e ), as a function of the distance from the source and the gas velocity. The presence of dust grains in the jet is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. Results. The detected lines show broad velocity profiles at the base of the jet (up to ∼100 km s −1 ), where up to three velocity components are detected. At 5 from the source, however, only the denser and more excited high-velocity components survive and the lines are narrower (∼10-30 km s −1 ). The jet is strongly asymmetric in the velocity and in its physical structure. The red lobe, which is slower (∼140 km s −1 ) and more collimated (opening angle: α ∼ 3-4 • ), presents low ionisation fractions (x e ∼ 0.1-0.4) and temperatures (T e < 5 × 10 3 K), while the total density is up to ∼2.5 × 10 4 cm −3 . The blue lobe, faster (∼-320 km s −1 ) and less collimated (α ∼ 14 • ), is also less dense (n H < 10 4 cm −3 ), but highly excited (T e up to ∼5 × 10 4 K and x e up to 0.9). The estimated mass-loss rate turns out to be similar in the two lobes (∼6-8 × 10 −9 M yr −1 ), while the flux of the linear momentum is three times higher in the blue one (∼2.5 × 10 −7 M yr −1 km s −1 ). Calcium is strongly depleted with respect to its solar abundance, indicating that the jet contains dust grains. The depletion is lower for higher velocities, which is consistent with dust destruction by shocks. Conclusions. The similar mass-loss rate in the two lobes suggests that the ejection power is comparable on the two sides of the system, as expected from a magneto-centrifugal ejection mechanism, and that the observed asymmetries are caused by a different mass load and propagation properties in an inhomogeneous environment. The presence of dust grains implies that the jet is generated from a region of the disc extending beyond the dust sublimation radius.

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Hubble Space TelescopeSpace Telescope Imaging Spectrograph Observations of the Bipolar Jet from RW Aurigae: Tracing Outflow Asymmetries Close to the Source

Cited by 132 publications

References 27 publications

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

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

The excitation of planetary orbits by stellar jet variability and polarity reversal

Tracing kinematical and physical asymmetries in the jet from DG Tauri B

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