Debris disc stirring by secular perturbations from giant planets
By A. Mustill, Mark Wyatt IoA, Cambridge, UK.. 2009
134 citations recorded by the source corpus.
Detectable debris discs are thought to require dynamical excitation (`stirring'), so that planetesimal collisions release large quantities of dust. We investigate the effects of the secular perturbations of a planet, which may lie at a significant distance from the planetesimal disc, to see if these perturbations can stir the disc, and if so over what time-scale. The secular perturbations cause orbits at different semimajor axes to precess at different rates, and after some time tcross initially non-intersecting orbits begin to cross. We show that tcross ~ a_disc^9/2 /(m_pl e_pl a_pl^3), where mpl, epl and apl are the mass, eccentricity and semimajor axis of the planet, and adisc is the semimajor axis of the disc. This time-scale can be faster than that for the growth of planetesimals to Pluto's size within the outer disc. We also calculate the magnitude of the relative velocities induced among planetesimals and infer that a planet's perturbations can typically cause destructive collisions out to 100 s of au. Recently formed planets can thus have a significant impact on planet formation in the outer disc which may be curtailed by the formation of giant planets much closer to the star. The presence of an observed debris disc does not require the presence of Pluto-sized objects within it, since it can also have been stirred by a planet not in the disc. For the star ∊ Eridani, we find that the known radial velocity planet can excite the planetesimal belt at 60au sufficiently to cause destructive collisions of bodies up to 100km in size, on a time-scale of 40Myr. (Less)
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/d257a7ee9c22a38a647221964095406a0ee5ae7a
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In Astronomy and Astrophysics
Citations in the corpus
- Debris disks as signposts of terrestrial planet formation (2011, background): “Mustill & Wyatt (2009) showed that self-stirred planetesimal disks tend to be fainter than disks stirred by giant planets.”