Astrophysics

Planetary Confinement

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Science  04 May 2012:
Vol. 336, Issue 6081, pp. 520
DOI: 10.1126/science.336.6081.520-a
CREDIT: ALMA (ESO/NAOJ/NRAO)

Located 25 light-years away, the star Fomalhaut is surrounded by a spectacular eccentric disk of dust and debris somewhat similar to the Kuiper Belt in our solar system. Boley et al. traced the parent body population for this debris disk using observations of millimeter-sized grains obtained with the Atacama Large Millimeter Array, an observatory under construction on the Chajnantor plateau, 5000 m altitude in northern Chile. The 350-GHz images, which trace grains that do not respond to stellar radiation and hence manifest orbits that do not move away from their birth region, show that the disk is both narrower and thinner than previously thought and has very sharp inner and outer edges. N-body simulations suggest that the disk is being confined by two planets with masses around that of Earth, one orbiting between the star and the disk and the other outside the disk. This is analogous to the confinement of Saturn's F ring by the moons Pandora and Prometheus and that of Uranus's ɛ ring by Cordelia and Ophelia.

Astrophys. J. 750, L21 (2012).

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