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Biology Articles » Astrobiology » The occurrence of Jovian planets and the habitability of planetary systems » Figures

Figures
- The occurrence of Jovian planets and the habitability of planetary systems

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Fig. 1.   Logarithm of the timescale versus logarithm of the semimajor axis for viscous dissipation of a gaseous disk, stellar wind dissipation of the disk, and migration of a one-Jupiter mass object. The migration model used is that of Ward et al. (28), and the viscous dissipation that of Hollenbach et al. (30). The turbulence parameter alpha is the dynamic viscosity divided by the product of the disk sound speed and vertical scale height. For small-to-moderate values of alpha, the timescales for both migration and disk dissipation are formally identical and depend only on the location of the orbit, the sound speed, and the turbulence parameter for the disk surrounding this solar mass star. For a highly turbulent disk (alpha = 10-2), other effects come into the migration to decrease its timescale relative to overall disk dissipation. Note that the dynamic timescales plotted here imply that the time available to make a Jupiter at 5 AU (heavy vertical line) is no more than a few million years for a quiescent disk and less than 104 years for a very turbulent disk.

Figure 1

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Fig. 2.   Metallicity enrichment in a one-solar-mass star versus the thickness of its well-mixed zone, expressed as mass fraction of the star. The lines are labeled with the number of Jupiter masses deposited in the star through planet migration. The metallicity enrichment is expressed through oxygen abundance; oxygen is assumed to be five times solar in the giant planets.

Figure 2

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Fig. 3.   Conceptual dependence of the supply of water to a terrestrial planet in the habitable zone for a system with a Jupiter-mass giant planet. The curve is drawn under the assumption that the solar system's configuration, with Jupiter near 5 AU, is close to the peak efficiency of delivery of water from hydrated ("wet") embryos in a primordial asteroid belt. The snowline is drawn in between 4 and 5 AU, but this is approximate. For a Jupiter with orbital semimajor axis of 3 AU or smaller around a solar-mass star, terrestrial planets in the habitable zone may not be stable,§ so water accreted is set to zero inward of that point. For a Jupiter at large semimajor axes, large numbers of icy planetesimals might get perturbed inward to collide with terrestrial planets (question mark on figure).

Figure 3

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Source: Proc. Natl. Acad. Sci. USA  vol. 98, n3, pp. 809-814, January 30, 2001.  


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