Three-dimensional modeling of radiative disks in binaries

• Published in: Astronomy and astrophysics (Berlin) 2013-08, Vol.556, p.1-15
• Main Authors: Picogna, G., Marzari, F.
• Format: Article
• Language: English
• Subjects: binaries: close; Computational fluid dynamics; Disks; Fluid flow; Hydraulics; hydrodynamics; Mathematical models; Morphology; Planet formation; planets and satellites: formation; protoplanetary disks; Spirals
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201321860

Context. Circumstellar disks in binaries are perturbed by the companion gravity causing significant alterations of the disk morphology. Spiral waves due to the companion tidal force also develop in the vertical direction and affect the disk temperature profile. These effects may significantly influence the process of planet formation. Aims. We perform 3D numerical simulations of disks in binaries with different initial dynamical configurations and physical parameters. Our goal is to investigate their evolution and their propensity to grow planets. Methods. We use an improved version of the SPH code VINE modified to better account for momentum and energy conservation via variable smoothing and softening length. The energy equation includes a flux-limited radiative transfer algorithm. The disk cooling is obtained with the use of “boundary particles” populating the outer surfaces of the disk and radiating to infinity. We model a system made of star/disk + star/disk where the secondary star (and relative disk) is less massive than the primary. Results. The numerical simulations performed for different values of binary separation and disk density show that trailing spiral shock waves develop when the stars approach their pericenter. Strong hydraulic jumps occur at the shock front, in particular for small separation binaries, creating breaking waves, and a consistent mass stream between the two disks. Both shock waves and mass transfer cause significant heating of the disk. At apocenter these perturbations are reduced and the disks are cooled down and less eccentric. Conclusions. The disk morphology is substantially affected by the companion perturbations, in particular in the vertical direction. The hydraulic jumps may slow down or even halt the dust coagulation process. The disk is significantly heated up by spiral waves and mass transfer, and the high gas temperature may prevent the ice condensation by moving the “snow line” outward. The disordered motion triggered by the spiral waves may, on the other hand, favor direct formation of large planetesimals from pebbles. The strength of the hydraulic jumps, disk heating, and mass exchange depends on the binary separation, and for larger semi-major axes, the tidal spiral pattern is substantially reduced. The environment then appears less hostile to planet formation.