The Effect of a Stellar Magnetic Variation on the Jet Velocity

Colle, Fabio De; Gracia, José; Murphy, Gareth

doi:10.1086/592494

Cited by 4 publications

(2 citation statements)

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“…These are often interpreted as internal shocks driven by relatively small perturbations in a steady ejection process, and which occur on typical time-scale between ∼ 5 − 20 years. For example in [18] it was shown that the temporal variability of the jet velocity may be associated with a time-varying stellar magnetic field. Episodic jet ejection behaviour may also be associated with variation in the accretion rates or an inflating stellar magnetosphere.…”

Section: Episodic Ejection Of Magnetic Bubbles and Jetsmentioning

confidence: 99%

Laboratory Studies of Astrophysical Jets

Ciardi

2009

Jets From Young Stars IV

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Jets and outflows produced during star-formation are observed on many scales: from the "micro-jets" extending a few hundred Astronomical Units to the "super-jets" propagating to parsecs distances. Recently, a new "class" of short-lived (hundreds of nano-seconds) centimetre-long jets has emerged in the laboratory as a complementary tool to study these complex astrophysical flows. Here I will discuss and review the recent work done on "simulating" protostellar jets in the laboratory using z-pinch machines.Comment: 25 Pages, 11 Figures to appear in Lecture Notes in Physics. Series Title: Jets from young stars IV: From models to observations and experiments Editors: P. J. V. Garcia and J. M. T. Ferreira. Publisher: Springe

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Section: Episodic Ejection Of Magnetic Bubbles and Jetsmentioning

confidence: 99%

Laboratory Studies of Astrophysical Jets

Ciardi

2009

Jets From Young Stars IV

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“…Hartmann 2009), the origin of knots along stellar jets (e.g. De Colle et al 2008b), the feedback of jets on the core and the star formation efficiency, and the interaction of jets with the ambient medium eventually leading to the generation of turbulence in molecular clouds (e.g. Carroll et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Tomographic Reconstruction of the Three-Dimensional Structure of the Hh30 Jet

Colle

Burgo

Raga

2010

ApJ

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The physical parameters of Herbig-Haro jets are usually determined from emission line ratios, obtained from spectroscopy or narrow band imaging, assuming that the emitting region is homogeneous along the line of sight. Under the more general hypothesis of axisymmetry, we apply tomographic reconstruction techniques to the analysis of Herbig-Haro jets. We use data of the HH30 jet taken by Hartigan & Morse (2007) with the Hubble space telescope using the slitless spectroscopy technique. Using a non-parametric Tikhonov regularization technique, we determine the volumetric emission line intensities of the [S II]λλ6716,6731, [O I]λ6300 and [N II]λ6583 forbidden emission lines. From our tomographic analysis of the corresponding line ratios, we produce "three-dimensional" images of the physical parameters. The reconstructed density, temperature and ionization fraction present much steeper profiles than those inferred using the assumption of homogeneity. Our technique reveals that the reconstructed jet is much more collimated than the observed one close to the source (a width ∼ 5 AU vs. ∼ 20 AU at a distance of 10 AU from the star), while they have similar widths at larger distances. In addition, our results show a much more fragmented and irregular jet structure than the classical analysis, suggesting that the the ejection history of the jet from the star-disk system has a shorter timescale component (∼ some months) superimposed on a longer, previously observed timescale (of a few years). Finally, we discuss the possible application of the same technique to other stellar jets and planetary nebulae.

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On the time variability of the HH jet ejection process

Colle

2010

Proc. IAU

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Abstract. Two-dimensional emission line images of the HH30 jet were recently used (De Colle et al. 2010) to recover the three-dimensional structure of the jet by applying standard tomographic technique ("Tikhonov regularization techniques"). In this paper I show that it is possible to determine the ejection history of the HH30 jet by directly comparing the outcome of numerical simulations with the results of the tomographic inversion. In particular, it is shown that the HH30 jet electron density map is best reproduced by assuming a velocity variation at the base of the jet with a large scale periodicity (with a period of ∼ 3 yrs) added to small scales velocity variation (with periods months).

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The Effect of a Stellar Magnetic Variation on the Jet Velocity

Cited by 4 publications

References 32 publications

Laboratory Studies of Astrophysical Jets

Laboratory Studies of Astrophysical Jets

Tomographic Reconstruction of the Three-Dimensional Structure of the Hh30 Jet

On the time variability of the HH jet ejection process

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