Intrinsically asymmetric astrophysical jets

Wang, J. C. L.; Sulkanen, M. E.; Lovelace, R. V. E.

doi:10.1086/171258

Cited by 44 publications

(30 citation statements)

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“…In stars with a complex magnetic field, outflows may be asymmetric due to the top-bottom asymmetry of the magnetic field (e.g., Wang et al 1992). For example, the superposition of an axisymmetric dipole field with a quadrupole field leads to a configuration in which the magnetic flux is larger on one side of the equatorial plane than the other (see Fig.…”

Section: Asymmetric and One-sided Outflowsmentioning

confidence: 99%

Accretion, Outflows, and Winds of Magnetized Stars

Romanova

Owocki

2015

Space Sci Rev

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Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

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Section: Asymmetric and One-sided Outflowsmentioning

confidence: 99%

Accretion, Outflows, and Winds of Magnetized Stars

Romanova

Owocki

2015

Space Sci Rev

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“…On the other hand, the accretion disk could also have a quadrupolar magnetic field originating either in the dynamo mechanism or advection (Aburihan et al 2001). In fact, it has been shown that nonbipolar disk field topologies can be a potential source of asymmetry in AGN jets (Wang et al 1992;Chagelishvili et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Velocity asymmetries in young stellar object jets

Matsakos

Vlahakis

Tsinganos

et al. 2012

A&A

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Context. It is well established that some YSO jets (e.g. RW Aur) display different propagation speeds between their blue and red shifted parts, a feature possibly associated with the central engine or the environment in which the jet propagates. Aims. To understand the origin of asymmetric YSO jet velocities, we investigate the efficiency of two candidate mechanisms, one based on the intrinsic properties of the system and the other on the role of the external medium. In particular, a parallel or anti-parallel configuration between the protostellar magnetosphere and the disk magnetic field is considered, and the resulting dynamics examined both in an ideal and in a resistive magneto-hydrodynamical (MHD) regime. Moreover, we explore the effects of a potential difference in the pressure of the environment, as a consequence of the nonuniform density distribution of molecular clouds. Methods. Ideal and resistive axisymmetric numerical simulations were carried out for a variety of models, all of which are based on a combination of two analytical solutions, a disk wind and a stellar outflow. The initial two-component jet is modified by either inverting the orientation of its inner magnetic field or imposing a constant surrounding pressure. The velocity profiles are studied by assuming steady flows as well as after strong time variable ejection is incorporated. Results. Discrepancies between the speeds of the two outflows in opposite directions can indeed occur both due to unaligned magnetic fields and different outer pressures. In the former case, the asymmetry appears only on the dependence of the velocity on the cylindrical distance, but the implied observed value is significantly altered when the density distribution is also taken into account. On the other hand, a nonuniform medium collimates the two jets unevenly, directly affecting their propagation speed. A further interesting feature of the pressure-confined outflow simulations is the formation of static knots whose spacing seems to be associated with the ambient pressure. Conclusions. Jet velocity asymmetries are anticipated both when multipolar magnetic moments are present in the star-disk system and when nonuniform environments are considered. The latter is an external mechanism that can easily explain the large timescale of the phenomenon, whereas the former naturally relates it to the YSO intrinsic properties.

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“…to get lopsided outflows was proposed earlier by Wang et al [90]. The time-scale during which the jet comes from the upper hemisphere is set by the evolution time-scale for the stellar magnetic field.…”

Section: Lopsided Jets and Outflows From Discsmentioning

confidence: 97%

Particle rings and astrophysical accretion discs

Lovelace¹,

Romanova²

2016

AIP Conference Proceedings

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Abstract. Norman Rostoker had a wide range of interests and significant impact on the plasma physics research at Cornell during the time he was a Cornell professor. His interests ranged from the theory of energetic electron and ion beams and strong particle rings to the related topics of astrophysical accretion discs. We outline some of the topics related to rings and discs including the Rossby wave instability which leads to formation of anticyclonic vortices in astrophysical discs. These vorticies are regions of high pressure and act to trap dust particles which in turn may facilitate planetesimals growth in proto-planetary disks and could be important for planet formation. Analytical methods and global 3D magneto-hydrodynamic simulations have led to rapid advances in our understanding of discs in recent years.

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Intrinsically asymmetric astrophysical jets

Cited by 44 publications

References 0 publications

Accretion, Outflows, and Winds of Magnetized Stars

Accretion, Outflows, and Winds of Magnetized Stars

Velocity asymmetries in young stellar object jets

Particle rings and astrophysical accretion discs

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