Publication Abstracts

Cabot et al. 1987

Cabot, W., V.M. Canuto, O. Hubickyj, and J.B. Pollack, 1987: The role of turbulent convection in the primitive solar nebula: II. Results. Icarus, 69, 423-457, doi:10.1016/0019-1035(87)90017-0.

Numerical results from a new model of the primordial solar nebula are presented in which convection is assumed to be the sole source of turbulence that causes the nebula to evolve. We introduce a new model of convective turbulence (described in detail in Paper I of this series) and new grain opacities computed from an improved physical model. The nebula is assumed to be in a stage prior to planetismal formation in which gas and dust grains are mixed homogeneously, but in a stage after significant infall of matter from the outer cloud. Vertical structures for a thin nebular disk are calculated for different radii and accretion rates assuming vertical hydrostatic and thermal equilibrium; radial sequences of vertical solutions are constructed for constant accretion rates to represent quasistatic disk structures. Some aspects of our results differ markedly from those done previously by Lin and co-workers. Our values for the turbulent efficiency α (10-2 to 10-4) are much lower and much more sensitive to opacity and surface density. Our low values of α result in (1) small turbulent speeds (≤1% of sound speed), which will alter prior computations of grain coagulation and sedimentation rates; (2) a more massive disk (>0.1 M) that becomes gravitationally unstable at outer (super-Uranian) orbits; (3) a lower "best value" of the accretion rate (∼1018.5 g/sec); and (4) a longer characteristic dispersal time for the disk (>2×106 years), which may greatly exceed that inferred from younger stellar objects. The high sensitivity of α on surface density produces an inverse accretion rate-surface density relationship, which implies that the Lightman-Eardley diffusive instability develops throughout a steady disk structure in the radial direction, causing the disk, at least at the onset, to separate into rings. Because radial gradients are neglected in the base disk structure, the manner in which the instability evolves to finite amplitude is unknown, but it could prevent the disk from reaching a quasistatic structure altogether. We conclude that convection may not be the dominant source of turbulence needed to evolve young solar/stellar nebulae, and may in fact be a disruptive mechanism in disk structure.

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BibTeX Citation

  author={Cabot, W. and Canuto, V. M. and Hubickyj, O. and Pollack, J. B.},
  title={The role of turbulent convection in the primitive solar nebula: II. Results},

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RIS Citation

ID  - ca03700t
AU  - Cabot, W.
AU  - Canuto, V. M.
AU  - Hubickyj, O.
AU  - Pollack, J. B.
PY  - 1987
TI  - The role of turbulent convection in the primitive solar nebula: II. Results
JA  - Icarus
JO  - Icarus
VL  - 69
SP  - 423
EP  - 457
DO  - 10.1016/0019-1035(87)90017-0
ER  -

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