A self-consistent model of mass and angular momentum transport in accretion disks

Properties have been demonstrated of the magneto-rotational instability for two different applications, i.e. for a global spherical model and a box simulation with Keplerian background shear flow. In both nonlinear cases a dynamo operates with a negative (positive) α-effect in the northern (southern) disk hemisphere and in both cases the angular momentum transport is outwards. Keplerian accretion disks should therefore exhibit large-scale magnetic fields with a dipolar geometry of the poloidal components favoring jet formation.

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Angular Momentum Transport in Accretion Disks

Cataclysmic Variables - Astrophysics and Space Science Library ◽

10.1007/978-94-011-0335-0_98 ◽

1995 ◽

pp. 349-358

Author(s):

Mario Livio

Keyword(s):

Angular Momentum ◽

Accretion Disks ◽

Momentum Transport ◽

Angular Momentum Transport

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Angular momentum transport in accretion disks: a hydrodynamical perspective

EAS Publications Series ◽

10.1051/eas/1982035 ◽

2019 ◽

Vol 82 ◽

pp. 391-413 ◽

Cited By ~ 5

Author(s):

S. Fromang ◽

G. Lesur

Keyword(s):

Angular Momentum ◽

Accretion Disk ◽

Accretion Disks ◽

Dynamical Evolution ◽

Theoretical Work ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Recent Developments ◽

The Many ◽

The Universe

The radial transport of angular momentum in accretion disk is a fundamental process in the universe. It governs the dynamical evolution of accretion disks and has implications for various issues ranging from the formation of planets to the growth of supermassive black holes. While the importance of magnetic fields for this problem has long been demonstrated, the existence of a source of transport solely hydrodynamical in nature has proven more difficult to establish and to quantify. In recent years, a combination of results coming from experiments, theoretical work and numerical simulations has dramatically improved our understanding of hydrodynamically mediated angular momentum transport in accretion disk. Here, based on these recent developments, we review the hydrodynamical processes that might contribute to transporting angular momentum radially in accretion disks and highlight the many questions that are still to be answered.

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Enhanced Angular Momentum Transport in Accretion Disks

Annual Review of Astronomy and Astrophysics ◽

10.1146/annurev.astro.41.081401.155207 ◽

2003 ◽

Vol 41 (1) ◽

pp. 555-597 ◽

Cited By ~ 312

Author(s):

Steven A. Balbus

Keyword(s):

Angular Momentum ◽

Accretion Disks ◽

Momentum Transport ◽

Angular Momentum Transport

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Angular Momentum Transport in Accretion Disks via Convection

The Astrophysical Journal ◽

10.1086/177328 ◽

1996 ◽

Vol 464 ◽

pp. 364 ◽

Cited By ~ 101

Author(s):

James M. Stone ◽

Steven A. Balbus

Keyword(s):

Angular Momentum ◽

Accretion Disks ◽

Momentum Transport ◽

Angular Momentum Transport

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Turbulence, Vorticity Generation and Angular Momentum Transport via the Baroclinic Instability in Accretion Disks

Symposium - International Astronomical Union ◽

10.1017/s0074180900218226 ◽

2004 ◽

Vol 202 ◽

pp. 350-352

Author(s):

Hubert Klahr ◽

Peter Bodenheimer

Keyword(s):

Angular Momentum ◽

Accretion Disks ◽

Baroclinic Instability ◽

Three Dimensional ◽

Gravitational Energy ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Accretion Rates ◽

Background Shear ◽

2D And 3D

We propose the global baroclinic instability as a source for vigorous turbulence leading to angular momentum transport in Keplerian accretion disks. We know from analytical considerations and three-dimensional radiation hydro simulations that, in particular, protoplanetary disks have a negative radial entropy gradient, which makes them baroclinic. Two-dimensional numerical simulations show that this baroclinic flow is unstable and produces turbulence. These findings were tested for numerical effects by performing barotropic simulations which show that imposed turbulence rapidly decays. The turbulence in baroclinic disks draws energy from the background shear, transports angular momentum outward and creates a radially inward bound accretion of matter, thus forming a self consistent process. Gravitational energy is transformed into turbulent kinetic energy, which is then dissipated, as in the classical accretion paradigm. We measure accretion rates in 2D and 3D simulations of Ṁ = −;10−9 to −10−7 M⊙ yr−1 and viscosity parameters of α = 10−4–10−2, which fit perfectly together and agree reasonably with observations. The turbulence creates pressure waves, Rossby waves, and vortices in the (R – ø) plane of the disk. We demonstrate in a global simulation that these vortices tend to form out of little background noise and to be long-lasting features, which have already been suggested to lead to the formation of planets.

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First grids of low-mass stellar models and isochrones with self-consistent treatment of rotation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935160 ◽

2019 ◽

Vol 631 ◽

pp. A77 ◽

Cited By ~ 18

Author(s):

L. Amard ◽

A. Palacios ◽

C. Charbonnel ◽

F. Gallet ◽

C. Georgy ◽

...

Keyword(s):

Angular Momentum ◽

Open Clusters ◽

Momentum Transport ◽

Surface Boundary ◽

Angular Momentum Transport ◽

Solar Composition ◽

Self Consistent ◽

Low Mass ◽

Stellar Models ◽

The Impact

Aims.We present an extended grid of state-of-the art stellar models for low-mass stars including updated physics (nuclear reaction rates, surface boundary condition, mass-loss rate, angular momentum transport, rotation-induced mixing, and torque prescriptions). We evaluate the impact of wind braking, realistic atmospheric treatment, rotation, and rotation-induced mixing on the structural and rotational evolution from the pre-main sequence (PMS) to the turn-off.Methods.Using the STAREVOL code, we provide an updated PMS grid. We computed stellar models for seven different metallicities, from [Fe/H] = −1 dex to [Fe/H] = +0.3 dex with a solar composition corresponding toZ = 0.0134. The initial stellar mass ranges from 0.2 to 1.5M⊙with extra grid refinement around one solar mass. We also provide rotating models for three different initial rotation rates (slow, median, and fast) with prescriptions for the wind braking and disc-coupling timescale calibrated on observed properties of young open clusters. The rotational mixing includes the most recent description of the turbulence anisotropy in stably stratified regions.Results.The overall behaviour of our models at solar metallicity, and their constitutive physics, are validated through a detailed comparison with a variety of distributed evolutionary tracks. The main differences arise from the choice of surface boundary conditions and initial solar composition. The models including rotation with our prescription for angular momentum extraction and self-consistent formalism for angular momentum transport are able to reproduce the rotation period distribution observed in young open clusters over a wide range of mass values. These models are publicly available and can be used to analyse data coming from present and forthcoming asteroseismic and spectroscopic surveys such asGaia, TESS, and PLATO.

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