The Interaction between a Pulsed Astrophysical Jet and Small‐Scale Heterogeneous Media

Yirak, Kristopher; Frank, Adam; Cunningham, A. J.; Mitran, Sorin

doi:10.1086/523955

Cited by 13 publications

(11 citation statements)

References 42 publications

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“…as "hypersonic buckshot" (e.g. Yirak et al 2008Yirak et al , 2009Yirak et al , 2010, but our results show that much more work needs to be done in this domain. The structure of jets is a question of fundamental importance because it speaks directly to processes occurring close to the star-disk system where the jet is launched, and considerable uncertainty remains as to how this process operates.…”

Section: Discussionmentioning

confidence: 85%

FLUID DYNAMICS OF STELLAR JETS IN REAL TIME: THIRD EPOCHHUBBLE SPACE TELESCOPEIMAGES OF HH 1, HH 34, AND HH 47

Hartigan

Frank

Foster

et al. 2011

ApJ

101

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We present new, third-epoch HST Hα and [S II] images of three HH jets (HH 1&2, HH 34, and HH 47) and compare these images with those from the previous epochs. The high-spatial resolution, coupled with a time-series whose cadence is of order both the hydrodynamical and radiative cooling timescales of the flow allows us to follow the hydrodynamical/magnetohydrodynamical evolution of an astrophysical plasma system in which ionization and radiative cooling play significant roles. Cooling zones behind the shocks are resolved, so it is possible to identify which way material flows through a given shock wave. The images show that heterogeneity is paramount in these jets, with clumps dominating the morphologies of both bow shocks and their Mach disks. This clumpiness exists on scales smaller than the jet widths and determines the behavior of many of the features in the jets. Evidence also exists for considerable shear as jets interact with their surrounding molecular clouds, and in several cases we observe shock waves as they form and fade where material emerges from the source and as it proceeds along the beam of the jet. Fine-structure within two extended bow shocks may result from Mach stems that form at the intersection points of oblique shocks within these clumpy objects. Taken together, these observations represent the most significant foray thus far into the time domain for stellar jets, and comprise one of the richest data sets in existence for comparing the behavior of a complex astrophysical plasma flows with numerical simulations and laboratory experiments.

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Section: Discussionmentioning

confidence: 85%

FLUID DYNAMICS OF STELLAR JETS IN REAL TIME: THIRD EPOCHHUBBLE SPACE TELESCOPEIMAGES OF HH 1, HH 34, AND HH 47

Hartigan

Frank

Foster

et al. 2011

ApJ

101

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“…In many environments flows interact not with a single cloud, but with many clouds. Hydrodynamic simulations of the complex interactions between multiple clouds and a tenuous flow have been studied by Jun, Jones & Norman (1996), Poludnenko, Frank & Blackman (2002), Steffen & López (2004), Melioli, de Gouveia Dal Pino & Raga (2005), Pittard et al (2005), Tenorio‐Tagle et al (2006), Sutherland & Bicknell (2007), Cooper et al (2008) and Yirak et al (2008). Most of these works focused on the changes to the global flow, but the interaction between two or more long‐lived clouds in close proximity has been examined in detail by Pittard et al (2005).…”

Section: Future Workmentioning

confidence: 99%

The turbulent destruction of clouds - I. Ak-ε treatment of turbulence in 2D models of adiabatic shock-cloud interactions

Pittard

Falle

Hartquist

et al. 2009

Monthly Notices of the Royal Astronomical Society

162

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The interaction of a shock with a cloud has been extensively studied in the literature, where the effects of magnetic fields, radiative cooling and thermal conduction have been considered. In many cases, the formation of fully developed turbulence has been prevented by the artificial viscosity inherent in hydrodynamical simulations. This problem is particularly severe in some recent simulations designed to investigate the interaction of a flow with multiple clouds, where the resolution of individual clouds is necessarily poor. Furthermore, the shocked flow interacting with the cloud has been assumed to be completely uniform in all previous single‐cloud studies. In reality, the flow behind the shock is also likely to be turbulent, with non‐uniform density, pressure and velocity structure created as the shock sweeps over inhomogeneities upstream of the cloud (as seen in recent multiple cloud simulations). To address these twin issues we use a subgrid compressible k–ε turbulence model to estimate the properties of the turbulence generated in shock–cloud interactions and the resulting increase in the transport coefficients that the turbulence brings. A detailed comparison with the output from an inviscid hydrodynamical code puts these new results into context. Despite the above concerns, we find that cloud destruction in inviscid and k–ε models occurs at roughly the same speed when the post‐shock flow is smooth and when the density contrast between the cloud and intercloud medium, χ≲ 100. However, there are increasing and significant differences as χ increases. The k–ε models also demonstrate better convergence in resolution tests than inviscid models, a feature which is particularly useful for multiple‐cloud simulations. Clouds which are over‐run by a highly turbulent post‐shock environment are destroyed significantly quicker as they are subject to strong ‘buffeting’ by the flow. The decreased lifetime and faster acceleration of the cloud material to the speed of the ambient flow leads to a reduction in the total amount of circulation (vorticity) generated in the interaction, so that the amount of vorticity may be self‐limiting. Additional calculations with an inviscid code where the post‐shock flow is given random, grid‐scale, motions confirm the more rapid destruction of the cloud. Our results clearly show that turbulence plays an important role in shock–cloud interactions, and that environmental turbulence adds a new dimension to the parameter space which has hitherto been studied.

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“…Interestingly, new modelling that incorporates these mechanisms has been recently published. Yirak et al (2008) and Yirak et al (2009) performed more complex, two‐dimensional hydrodynamical simulations of jets that propagate through a small‐scale inhomogeneous environment (e.g. clumps with a size smaller than the jet beam).…”

Section: Discussionmentioning

confidence: 99%

The complex structure of HH 110 as revealed from Integral Field Spectroscopy

López

García-Lorenzo

Sanchez

et al. 2010

Monthly Notices of the Royal Astronomical Society

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The Interaction between a Pulsed Astrophysical Jet and Small‐Scale Heterogeneous Media

Cited by 13 publications

References 42 publications

FLUID DYNAMICS OF STELLAR JETS IN REAL TIME: THIRD EPOCHHUBBLE SPACE TELESCOPEIMAGES OF HH 1, HH 34, AND HH 47

FLUID DYNAMICS OF STELLAR JETS IN REAL TIME: THIRD EPOCHHUBBLE SPACE TELESCOPEIMAGES OF HH 1, HH 34, AND HH 47

The turbulent destruction of clouds - I. Ak-ε treatment of turbulence in 2D models of adiabatic shock-cloud interactions

The complex structure of HH 110 as revealed from Integral Field Spectroscopy

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