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Astronomy and Astrophysics 545 (2012) A134
Dust-trapping Rossby vortices in protoplanetary disks
H. Meheut, Z. Meliani 1, P. Varniere 2, W. Benz
(09/2012)

Context. One of the most challenging steps in planet formation theory is the one leading to the formation of planetesimals of kilometre size. A promising scenario involves the existence of vortices able to concentrate a large amount of dust and grains in their centres. Up to now this scenario has mostly been studied in 2D razor thin disks. A 3D study including, simultaneously, the formation and resulting dust concentration of the vortices with vertical settling, is still missing. Aims: The Rossby wave instability self-consistently forms 3D vortices, which have the unique quality of presenting a large-scale vertical velocity in their centre. Here we aim to study how this newly discovered effect can alter the dynamic evolution of the dust. Methods: We performed global 3D simulations of the RWI in a radially and vertically stratified disk using the code MPI-AMRVAC. After the growth phase of the instability, the gas and solid phases are modelled by a bi-fluid approach, where the dust is considered as a fluid without pressure. Both the drag force of the gas on the dust and the back reaction of the dust on the gas are included. Multiple grain sizes from 1 mm to 5 cm are used with a constant density distribution. Results: We obtain in a short timescale a high concentration of the largest grains in the vortices. Indeed, in 3 rotations the dust-to-gas density ratio grows from 10-2 to unity leading to a concentration of mass up to that of Mars in one vortex. The presence of the radial drift is also at the origin of a dust pile-up at the radius of the vortices. Lastly, the vertical velocity of the gas in the vortex causes the sedimentation process to be reversed, the mm size dust is lifted and higher concentrations are obtained in the upper layer than in the midplane. Conclusions: The Rossby wave instability is a promising mechanism for planetesimal formation, and the results presented here can be of particular interest in the context of future observations of protoplanetary disks.
1 :  Laboratoire Univers et Théories (LUTH)
CNRS : UMR8102 – INSU – Observatoire de Paris – Université Paris VII - Paris Diderot
2 :  AstroParticule et Cosmologie (APC - UMR 7164)
CNRS : UMR7164 – IN2P3 – Observatoire de Paris – Université Paris VII - Paris Diderot – CEA : DSM/IRFU
APC - ADAMIS
Physique/Astrophysique/Planétologie et astrophysique de la terre

Planète et Univers/Astrophysique/Planétologie et astrophysique de la terre

Physique/Astrophysique/Astrophysique stellaire et solaire

Planète et Univers/Astrophysique/Astrophysique stellaire et solaire
planets and satellites: formation – protoplanetary disks – hydrodynamics – instabilities – accretion – accretion disks
Lien vers le texte intégral : 
http://fr.arXiv.org/abs/1208.4947

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