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Dust-trapping Rossby vortices in protoplanetary disks
Meheut H., Meliani Z., Varniere P., Benz W.
Astronomy and Astrophysics 545 (2012) A134 - http://hal.archives-ouvertes.fr/hal-00736574
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
Dust-trapping Rossby vortices in protoplanetary disks
H. Meheut, Z. Meliani1, P. Varniere2, W. Benz
1 :  LUTH - Laboratoire Univers et Théories
CNRS : UMR8102 – INSU – Observatoire de Paris – Université Paris VII - Paris Diderot
5 place Jules Janssen 92195 Meudon cedex
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
CNRS : UMR7164 – IN2P3 – Observatoire de Paris – Université Paris VII - Paris Diderot – CEA : DSM/IRFU
APC - UMR 7164, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, case postale 7020, F-75205 Paris Cedex 13
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.

Astronomy and Astrophysics (Astron. Astrophys.)
Publisher EDP Sciences
ISSN 0004-6361 (eISSN : 1432-0756)
Articles dans des revues avec comité de lecture

planets and satellites: formation – protoplanetary disks – hydrodynamics – instabilities – accretion – accretion disks
Accepted for publication in Astronomy and Astrophysics

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