Spiral modes driven by narrow features in angular-momentum density

Sellwood, J. A.; Kahn, F. D.

doi:10.1093/mnras/250.2.278

Cited by 105 publications

(144 citation statements)

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“…In the above models, the evolution of the spiral arms is governed by the winding of the arms, which leads to breaks and bifurcations of the spiral arms. Sellwood & Lin (1989) and Sellwood & Kahn (1991) instead argued that the dynamics originate from multiple wave modes of Figure 10. Evolution of spiral arm on α −δ plane for T rot = 12.0 − 12.5.…”

Section: Swing Amplified Spiralsmentioning

confidence: 99%

Dawes Review 4: Spiral Structures in Disc Galaxies

Dobbs

Baba

2014

Publ. Astron. Soc. Aust.

250

272

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The majority of astrophysics involves the study of spiral galaxies, and stars and planets within them, but how spiral arms in galaxies form and evolve is still a fundamental problem. Major progress in this field was made primarily in the 1960s, and early 1970s, but since then there has been no comprehensive update on the state of the field. In this review, we discuss the progress in theory, and in particular numerical calculations, which unlike in the 1960s and 1970s, are now commonplace, as well as recent observational developments. We set out the current status for different scenarios for spiral arm formation, the nature of the spiral arms they induce, and the consequences for gas dynamics and star formation in different types of spiral galaxies. We argue that, with the possible exception of barred galaxies, spiral arms are transient, recurrent and initiated by swing amplified instabilities in the disc. We suppose that unbarred m = 2 spiral patterns are induced by tidal interactions, and slowly wind up over time. However the mechanism for generating spiral structure does not appear to have significant consequences for star formation in galaxies.

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Section: Swing Amplified Spiralsmentioning

confidence: 99%

Dawes Review 4: Spiral Structures in Disc Galaxies

Dobbs

Baba

2014

Publ. Astron. Soc. Aust.

250

272

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“…The RWI (Lovelace et al 1999;Li et al 2000Li et al , 2001 has been studied and discussed in various situations of differentially rotating discs, from galactic discs (Lovelace & Hohlfeld 1978;Sellwood & Kahn 1991) to microquasar and protoplanetary discs (Papaloizou & Pringle 1985;Lovelace et al 1999). It can be seen as the form that the Kelvin-Helmholtz instability takes in differentially rotating discs, and has a similar instability criterion: it requires an extremum in a vorticity-related quantity, defined in a non-magnetised thin disc as (Li et al 2000)…”

Section: Rossby Wave Instabilitymentioning

confidence: 99%

Formation and long-term evolution of 3D vortices in protoplanetary discs

Méheut¹,

Keppens²,

Casse³

et al. 2012

A&A

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Context. In the context of planet formation, anticyclonic vortices have recently received much attention for the role they can play in planetesimal formation. Radial migration of intermediate-size solids towards the central star may prevent them from growing to larger solid grains. On the other hand, vortices can trap the dust and accelerate this growth, counteracting fast radial transport. Several effects have been shown to affect this scenario, such as vortex migration or decay. Aims. We aim to study the formation of vortices by the Rossby wave instability and their long-term evolution in a full threedimensional (3D) protoplanetary disc. Methods. We used a robust numerical scheme combined with adaptive mesh refinement in cylindrical coordinates, which allowed us to affordably compute long-term 3D evolutions. We considered a full disc radially and vertically stratified, in which vortices can be formed by the Rossby wave instability. Results. We show that the 3D Rossby vortices grow and survive over hundreds of years without migration. The localised overdensity that initiated the instability and vortex formation survives the growth of the Rossby wave instability for very long times. When the vortices are no longer sustained by the Rossby wave instability, their shape changes towards more elliptical vortices. This allows them to survive shear-driven destruction, but they may be prone to elliptical instability and slow decay. Conclusions. When the conditions for growing Rossby-wave-related instabilities are maintained in the disc, large-scale vortices can survive over very long timescales and may be able to concentrate solids.

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“…Only a small bump or depression in L(r) leads to the growth of a global disc mode (Sellwood 2013). When the self-gravity of the disc is strong, the RWI is observed to occur at radii where L is a minimum rather than a maximum (Sellwood and Kahn 1991;Sellwood 2012Sellwood , 2013 as predicted by Lovelace and Hohlfeld (1978).…”

Section: Vortices In Self-graviating Discsmentioning

confidence: 87%

“…For disc galaxies L → σΩ/κ 2 (Lovelace and Hohlfeld 1978), where κ is the radial epicyclic angular frequency given below equation 3. The RWI in disc galaxies consisting predominanly of stars has been observed and studied in many different cases using N −body simulations (Sellwood and Kahn 1991;Sellwood 2012;Sellwood 2013). Only a small bump or depression in L(r) leads to the growth of a global disc mode (Sellwood 2013).…”

Section: Vortices In Self-graviating Discsmentioning

confidence: 99%

Rossby wave instability in astrophysical discs

Lovelace

Romanova

2014

Fluid Dyn. Res.

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Abstract.A brief review is given of the Rossby wave instability (RWI) in astrophysical discs. In non-self-gravitating discs, around for example a newly forming stars, the instability can be triggered by an axisymmetric bump at some radius r 0 in the disc surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation [∝ exp(imφ), m = 1, 2..] in the vicinity of r 0 consisting of anticyclonic vortices. These vortices are regions of high pressure and consequently act to trap dust particles which in turn can facilitate planetesimal growth in proto-planetary discs. The Rossby vortices in the discs around stars and black holes may cause the observed quasi-periodic modulations of the disc's thermal emission.

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Spiral modes driven by narrow features in angular-momentum density

Cited by 105 publications

References 0 publications

Dawes Review 4: Spiral Structures in Disc Galaxies

Dawes Review 4: Spiral Structures in Disc Galaxies

Formation and long-term evolution of 3D vortices in protoplanetary discs

Rossby wave instability in astrophysical discs

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