Time-dependent models of the structure and stability of self-gravitating protoplanetary discs

• Published in: Monthly notices of the Royal Astronomical Society Vol. 396; no. 4; pp. 2228 - 2236
• Main Authors: Rice, W. K. M., Armitage, Philip J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 11-07-2009; Wiley-Blackwell; Oxford University Press
• Subjects: Accretion disks; Astronomy; Astrophysics; circumstellar matter; Earth, ocean, space; Exact sciences and technology; Gravity; planetary systems: formation; planetary systems: protoplanetary discs; Planets; Star & galaxy formation; stars: formation; stars: pre-main-sequence; stars: formation; stars: pre-main-sequence; planetary systems: protoplanetary discs; circumstellar matter; planetary systems: formation; Angular momentum transfer; Turbulence; Accretion rate; Central stars; Circumstellar matter; High temperature; Planetary system; Fragmentation; Planetary cosmogony; Star formation; Instability; Models; Self-gravitating systems; Gravity
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2009.14879.x

Angular momentum transport within young massive protoplanetary discs may be dominated by self-gravity at radii where the disc is too weakly ionized to allow the development of the magneto-rotational instability. We use time-dependent one-dimensional disc models, based on a local cooling time calculation of the efficiency of transport, to study the radial structure and stability (against fragmentation) of protoplanetary discs in which self-gravity is the sole transport mechanism. We find that self-gravitating discs rapidly attain a quasi-steady state in which the surface density in the inner disc is high and the strength of turbulence very low (α∼ 10−3 or less inside 5 au). Temperatures high enough to form crystalline silicates may extend out to several astronomical units at early times within these discs. None of our discs spontaneously develop regions that would be unambiguously unstable to fragmentation into substellar objects, though the outer regions (beyond 20 au) of the most massive discs are close enough to the threshold that fragmentation cannot be ruled out. We discuss how the mass accretion rates through such discs may vary with disc mass and with mass of the central star, and note that a determination of the relation for very young systems may allow a test of the model.