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

Podio, L.; Eislöffel, J.; Melnikov, S.; Hodapp, Klaus W.; Bacciotti, F.

doi:10.1051/0004-6361/201016049

Cited by 51 publications

(73 citation statements)

References 60 publications

(172 reference statements)

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“…Interestingly, the same property is observed in other asymmetric jets (RW Aur, Hartigan & Hillenbrand 2009; DG Tau B, Podio et al 2011). For all three objects, the relative velocity dispersion is higher than what is expected by projection effects given the jet opening angle (see also Hartigan & Hillenbrand 2009).…”

Section: Asymmetrymentioning

confidence: 54%

“…Various explanations have been proposed, including an asymmetric disk structure or magnetic field configuration, or propagation in an asymmetric environment (Ferreira et al 2006;Matsakos et al 2012;Fendt & Sheikhnezami 2013). In some cases, the mass-loss rate is found to be similar in both lobes despite the velocity asymmetry, suggesting external conditions cause their different appearance (Melnikov et al 2009;Podio et al 2011). In other systems, like HH 1042 , the mean velocity and mass-loss rate are similar on both sides, but velocity modulations are different, indicating a non-synchronized launching mechanism.…”

Section: Asymmetrymentioning

confidence: 99%

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Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Ellerbroek

Podio

Dougados

et al. 2014

A&A

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131

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Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ∼16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity, and shock conditions are asymmetric. We findṀ jet /Ṁ acc ∼ 0.01−0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.

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Section: Asymmetrymentioning

confidence: 54%

Section: Asymmetrymentioning

confidence: 99%

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Ellerbroek

Podio

Dougados

et al. 2014

A&A

Self Cite

131

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“…This suggests that between the jet, traced by the [Fe ] lines, and the protostar a dusty shell or the disk might further obscure the photosphere. This phenomenon is not uncommon; for example, the extinction towards DG Tau B is much higher than the extinction derived from its jet emission lines (Podio et al 2011).…”

Section: Extinctionmentioning

confidence: 99%

The outflow history of two Herbig-Haro jets in RCW 36: HH 1042 and HH 1043

Ellerbroek

Podio

Kaper

et al. 2013

A&A

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Jets around low-and intermediate-mass young stellar objects (YSOs) contain a fossil record of the recent accretion and outflow activity of their parent star-forming systems. We aim to understand whether the accretion/ejection process is similar across the entire stellar mass range of the parent YSOs. To this end we have obtained optical to near-infrared spectra of HH 1042 and HH 1043, two newly discovered jets in the massive star-forming region RCW 36, using X-shooter on the ESO Very Large Telescope. HH 1042 is associated with the intermediate-mass YSO 08576nr292. Over 90 emission lines are detected in the spectra of both targets. Highvelocity (up to 220 km s −1 ) blue-and redshifted emission from a bipolar flow is observed in typical shock tracers. Low-velocity emission from the background cloud is detected in nebular tracers, including lines from high ionization species. We applied combined optical and infrared spectral diagnostic tools in order to derive the physical conditions (density, temperature, and ionization) in the jets. The measured mass outflow rates areṀ jet ∼ 10 −7 M yr −1 . It is not possible to determine a reliable estimate for the accretion rate of the driving source of HH 1043 using optical tracers. We measure a high accretion rate for the driving source of HH 1042 (Ṁ acc ∼ 10 −6 M yr −1 ). For this system the ratioṀ jet /Ṁ acc ∼ 0.1, which is comparable to low-mass sources and consistent with models for magneto-centrifugal jet launching. The knotted structure and velocity spread in both jets are interpreted as fossil signatures of a variable outflow rate. While the mean velocities in both lobes of the jets are comparable, the variations in mass outflow rate and velocity in the two lobes are not symmetric. This asymmetry suggests that the launching mechanism on either side of the accretion disk is not synchronized. For the HH 1042 jet, we have constructed an interpretative physical model with a stochastic or periodic outflow rate and a description of a ballistic flow as its constituents. We have simulated the flow and the resulting emission in position−velocity space, which is then compared to the observed kinematic structure. The knotted structure and velocity spread can be reproduced qualitatively with the model. The results of the simulation indicate that the outflow velocity varies on timescales on the order of 100 yr.Key words. circumstellar matter -ISM: jets and outflows -ISM: individual objects: HH 1042 -stars: formation -ISM: individual objects: HH 1043 -Herbig-Haro objects IntroductionAstrophysical jets are a ubiquitous signature of accretion. When the magnetic field of the circumstellar disk is coupled to a jet, magnetic torques can remove a significant fraction of the system's angular momentum and mass through the jet, when charged particles are ejected. Jets exist in accreting systems on various scales, ranging from young stellar objects (YSOs) up to evolved binary systems and active galactic nuclei (AGNs). They are detected in emission lines at all wavelengths, from the ra...

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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%

“…Orbital excitation through stellar jets is based on jet-counterjet asymmetry that has been observed in a significant fraction of star-disk systems (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;. As the planet orbits around the star and the inner disk, it sees that system accelerating away from it owing to asymmetric momentum loss.…”

Section: Introductionmentioning

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

Cited by 51 publications

References 60 publications

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

The outflow history of two Herbig-Haro jets in RCW 36: HH 1042 and HH 1043

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

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