Stellar jets with intrinsically variable sources

Raga, A. C.; Cantó, J.; Binette, L.; Calvet, Nuria

doi:10.1086/169443

Cited by 216 publications

(201 citation statements)

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“…These sharp drops in velocity at the positions of the knots are in qualitative agreement with what one would expect from an interpretation of the knots as internal working surfaces resulting from an ejection velocity time variability (see, e.g., Raga et al 1990;de Gouveia dal Pino & Benz 1994). We find that the regions in between the knots have somewhat more confusing kinematic characteristics.…”

Section: Position-velocity Diagrams and Line Ratiossupporting

confidence: 87%

Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph

Raga

Noriega-Crespo

Reipurth

et al. 2002

The Astrophysical Journal

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We present a long-slit spectrum of the Herbig-Haro object HH 111, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. This spectrum has a spectral resolution of ≈50 km s Ϫ1 , so it gives a good picture of the kinematical properties of the observed object at very high angular resolution. We find that some of the knots along the jet are associated with sudden drops in the radial velocity (modulus), confirming that the emission from the knots is formed in shocks. We interpret the observed position-velocity diagrams in terms of a model of a jet from a variable source, and we attempt to carry out a reconstruction of the ejection velocity variability necessary for reproducing the observed kinematical structure.

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Section: Position-velocity Diagrams and Line Ratiossupporting

confidence: 87%

Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph

Raga

Noriega-Crespo

Reipurth

et al. 2002

The Astrophysical Journal

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“…The former possibility follows from the analysis of time-variable winds presented by González & Cantó (2002). If the velocity of the wind powered by a young star suddenly increases from an initial value v 0 to a final faster value av 0 (with a > 1), then a propagating working surface (two-wave structure; Raga et al 1990) is created that can produce significant free-free emission. The change in velocity may be accompanied by a modification in the mass-loss rate, from an initial value ofṀ 0 to a final value of bṀ 0 .…”

Section: Discussion Of the Extended Component In T Tau Srmentioning

confidence: 99%

On the Nature of the Extended Radio Emission Surrounding T Tauri South

Loinard¹,

Rodrı́guez²,

D’Alessio³

et al. 2007

ApJ

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At centimeter wavelengths, the young stellar system T Tauri is known to be composed of two sources, the northern one associated with the optical star T Tau itself, and the southern one related to the infrared companion T Tau S. Here we reexamine the origin of the radio emission from these two components using archival 2 cm, 3.6 cm, and 6 cm VLA observations. The emission from the northern member is confirmed to be largely dominated by free-free radiation from an ionized wind, while the southern radio source is confirmed to consist of a compact component of magnetic origin, surrounded by an extended halo. Only moderately variable, the extended structure associated with the southern source is most likely the result of free-free radiation related to stellar winds. However, its flat spectral energy distribution, its extent, and the lack of variation of its size with the frequency of observation are incompatible with the classical picture of a fully ionized wind with constant velocity and mass-loss rate leading to an electron density distribution of n e (r) / r À2 . Instead, we propose a model in which the ionization results from the impact of a supersonic wind driven by T Tau Sb onto dense surrounding material, possibly associated with the circumbinary disk recently identified around the T Tau Sa /T Tau Sb pair. The timescales for cooling and recombination in such a situation are in good agreement with the observed morphological changes undergone by the extended structure as its driving source moves through the environment.

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“…This model is inspired by the approach of Raga et al (1990), who solved the inviscid Burgers equation for a variable flow in one dimension. In later work (Raga et al 2012) it was shown that the shock fronts (i.e.…”

Section: "Interaction Physics": Model For a Ballistic Flowmentioning

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 jets with intrinsically variable sources

Cited by 216 publications

References 0 publications

Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph

Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph

On the Nature of the Extended Radio Emission Surrounding T Tauri South

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

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