E yrs

Edge

Edge

Figure 12. Inner rings of a tcool = 2 simulation at a late time in the asymptotic phase. The £ curves are azimuthally averaged surface densities. The ABR and SBR, the active and secondary boundary rings, are nearly axisymmetric in structure. The numbered bars along the bottom indicate where inner Lindblad resonances with outer disk patterns can be detected by Fourier analysis. The numbers indicate the m-value or armedness of the modes. Note that resonances seem to straddle all strong radial concentrations of mass, including the ABR and SBR. This figure is from Durisen et al. (2005).

Figure 12. Inner rings of a tcool = 2 simulation at a late time in the asymptotic phase. The £ curves are azimuthally averaged surface densities. The ABR and SBR, the active and secondary boundary rings, are nearly axisymmetric in structure. The numbered bars along the bottom indicate where inner Lindblad resonances with outer disk patterns can be detected by Fourier analysis. The numbers indicate the m-value or armedness of the modes. Note that resonances seem to straddle all strong radial concentrations of mass, including the ABR and SBR. This figure is from Durisen et al. (2005).

inactive disk interior to 10 AU produced by GIs in the active region beyond 10 AU. As in Fromang et al. (2004), alignments of corotation and Lindblad resonances seem to play a role in producing the radial hierarchy of modes. Note that the surface density of the ring labeled SBR, which contains about six Jupiter masses by the end of the calculation, has almost tripled in only 4,000 years. This simulation also suggests that waves propagate into the GI-inactive region from the GI-active side. Dissipation of these waves may keep the inner disk hot and may be a manifestation of the energy transport by waves expected for global GI behavior (Balbus & Papaloizou 1999).

The formation of rings and other dense structures by GIs, combined with the tendency for gas drag to sweep meter-sized and larger particles into them, as demonstrated by Haghighipour & Boss (2003a) and Rice et al. (2004), lead Durisen et al. (2005) to propose a hybrid planet-formation scenario. Long-lived, ring-like structures produced by GIs provide a safe haven in which cores can grow rapidly as solids drift to the ring centers, thereby accelerating planet formation by core accretion plus gas capture. Similar suggestions, that solids might accumulate at the centers of stable vortices or at disk edges, have been made previously by Klahr & Henning (1997) and Bryden et al. (2000), respectively. Dense gas rings additionally act as a barrier to type I migration and an inhibition to gap formation, and so the cores can grow to reasonable sizes and accrete the large envelopes necessary to make super-Jupiter mass objects. Self-gravity of the gas in the rings may also shorten the time necessary to accrete an envelope. Simulations to confirm the reality and robustness of GI-induced ring formation are underway. Core accretion simulations in the environment of a ring would also be very useful.

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