Numerical Simulations of Astrophysical Jets from Keplerian Disks. I. Stationary Models

Ouyed, Rachid; Pudritz, Ralph E.

doi:10.1086/304170

Cited by 264 publications

(291 citation statements)

References 44 publications

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“…Simultaneously, several numerical simulations have investigated the jet launching of these disk winds (e.g., Ouyed & Pudritz 1997;Ustyugova et al 2000;Krasnopolsky et al 2003;Casse & Keppens 2004). By investigating various boundary conditions and initial configurations, they confirmed that disk winds could indeed be accelerated and collimated by their own magnetic field.…”

Section: Disk Wind Theorymentioning

confidence: 82%

Nonradial and nonpolytropic astrophysical outflows

Sauty

Méliani

Lima

et al. 2011

A&A

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Context. A large sample of T Tauri stars exhibits optical jets, approximately half of which rotate slowly, only at ten per cent of their breakup velocity. The disk-locking mechanism has been shown to be inefficient to explain this observational fact. Aims. We show that low mass accreting T Tauri stars may have a strong stellar jet component that can effectively brake the star to the observed rotation speed. Methods. By means of a nonlinear separation of the variables in the full set of the MHD equations we construct semi-analytical solutions describing the dynamics and topology of the stellar component of the jet that emerges from the corona of the star. Results. We analyze two typical solutions with the same mass loss rate but different magnetic lever arms and jet radii. The first solution with a long lever arm and a wide jet radius effectively brakes the star and can be applied to the visible jets of T Tauri stars such as RY Tau. The second solution with a shorter lever arm and a very narrow jet radius may explain why similar stars, either weak line T Tauri stars (WTTS) or classical T Tauri stars (CTTS) do not all have visible jets. For instance, RY Tau itself seems to have different phases that probably depend on the activity of the star. Conclusions. First, stellar jets seem to be able to brake pre-main sequence stars with a low mass accreting rate. Second, jets may be visible only part time owing to changes in their boundary conditions. We also suggest a possible scenario for explaining the dichotomy between CTTS and WTTS, which rotate faster and do not have visible jets.

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Section: Disk Wind Theorymentioning

confidence: 82%

Nonradial and nonpolytropic astrophysical outflows

Sauty

Méliani

Lima

et al. 2011

A&A

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“…In case of massive protostellar systems that are formed deeply embedded in molecular clouds, they contribute to the feedback mechanism that can either halt or induce the infall process (Frank et al 2014). Numerical simulations predict the generation of jets from disk winds with the magnetic field playing a prominent role (Zanni et al 2007;Fendt 2006;Ouyed & Pudritz 1997). The regions close to the launch of protostellar jets have been examined using high resolution spectroscopy in optical wavebands leading to a better understanding ⋆ E-mail: sarita@iist.ac.in of the collimation properties and velocity structure at the base (Coffey, Bacciotti & Podio 2008).…”

Section: Introductionmentioning

confidence: 99%

Detection of non-thermal emission from the massive protostellar jet HH80-81 at low radio frequencies using GMRT

Vig

Veena

Mandal

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Low radio frequencies are favourable for the identification of emission from non-thermal processes such as synchrotron emission. The massive protostellar jet associated with IRAS 18162-2048 (also known as the HH80-81 system) has been imaged at low radio frequencies: 325, 610 and 1300 MHz, using the Giant Metrewave Radio Telescope, India. This is the first instance of detection of non-thermal emission from a massive protostellar jet at such low radio frequencies. The central region displays an elongated structure characteristic of the jet. In addition, the associated Herbig-Haro objects such as HH80, HH81, HH80N, and other condensations along the inner regions of the jet exhibit negative spectral indices. The spectral indices of most condensations are ∼ −0.7, higher than the value of −0.3 determined earlier using high frequency measurements. The magnetic field values derived using radio flux densities in the present work, under the assumption of equipartition near minimum energy condition, lie in the range 116 − 180 µG. We probe into the hard X-ray nature of a source that has been attributed to HH80, in an attempt to reconcile the non-thermal characteristics of radio and X-ray measurements. The flux densities of condensations at 610 MHz, measured nearly 11 yrs apart, display variability that could be ascribed to the cooling of condensations, and emphasize the importance of coeval or nearly-coeval measurements for estimation of spectral indices.

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“…Major progress has been made recently in the hydromagnetic regime of jet formation, originally proposed by Blandford & Payne (1982). Dynamic MHD simulations of the near-jet region have been carried out by several groups (Bell 1994 ;Ustyugova et al 1995Ustyugova et al , 1999Koldoba et al 1995 ;Romanova et al 1997Romanova et al , 1998Meier et al 1997 ;Ouyed & Pudritz 1997 ;Krasnopolsky, Li, & Blandford 1999). The simulation study of Ustyugova et al (1999) in the hydromagnetic wind regime indicates that the outÑows are accel-erated to superfast magnetosonic, superescape speeds close to their region of origin (D80 times the inner radius of the disk), whereas the collimation occurs at much larger distances.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Helix Formation Driven by Keplerian Disk Rotation in an External Plasma Pressure: The Initial Expansion Stage

Lovelace

Finn

et al. 2001

ApJ

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We study the evolution of a magnetic arcade that is anchored to an accretion disk and is sheared by the di †erential rotation of a Keplerian disk. By including an extremely low external plasma pressure at large distances, we obtain a sequence of axisymmetric magnetostatic equilibria and show that there is a fundamental di †erence between Ðeld lines that are a †ected by the plasma pressure and those that are not (i.e., force free). Force-free Ðelds, while being twisted by the di †erential rotation of the disk, expand outward at an angle of D60¡ away from the rotation axis, consistent with the previous studies. These force-free Ðeld lines, however, are enclosed by the outer Ðeld lines, which originate from small disk radii and come back to the disk at large radii. These outer Ðelds experience most of the twist, and they are also a †ected most by the external plasma pressure. At large cylindrical radial distances, magnetic pressure and plasma pressure are comparable so that any further radial expansion of magnetic Ðelds is prevented or slowed down greatly by this pressure. This hindrance to cylindrical radial expansion causes most of the added twist to be distributed on the ascending portion of the Ðeld lines, close to the rotation axis. Since these Ðeld lines are twisted most, the increasing ratio of the toroidal component to the B Õ poloidal component eventually results in the collimation of magnetic energy and Ñux around the B R,z rotation axis. We discuss the difficulty with adding a large number of twists within the limitations of the magnetostatic approximation.

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Numerical Simulations of Astrophysical Jets from Keplerian Disks. I. Stationary Models

Cited by 264 publications

References 44 publications

Nonradial and nonpolytropic astrophysical outflows

Nonradial and nonpolytropic astrophysical outflows

Detection of non-thermal emission from the massive protostellar jet HH80-81 at low radio frequencies using GMRT

Magnetic Helix Formation Driven by Keplerian Disk Rotation in an External Plasma Pressure: The Initial Expansion Stage

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