Nathan A. Kaib, Sean N. Raymond, Martin J. Duncan
Although the 55 Cnc system contains multiple, closely packed planets that are
presumably in a coplanar configuration, we use numerical simulations to
demonstrate that they are likely to be highly inclined to their parent star's
spin axis. Due to perturbations from its distant binary companion, this
planetary system precesses like a rigid body about its parent star.
Consequently, the parent star's spin axis and the planetary orbit normal likely
diverged long ago. Because only the projected separation of the binary is
known, we study this effect statistically, assuming an isotropic distribution
for wide binary orbits. We find that the most likely projected spin-orbit angle
is ~50 degrees, with a ~30% chance of a retrograde configuration. Transit
observations of the innermost planet - 55 Cnc e - may be used to verify these
findings via the Rossiter-McLaughlin effect. 55 Cancri may thus represent a new
class of planetary systems with well-ordered, coplanar orbits that are inclined
with respect to the stellar equator.
View original:
http://arxiv.org/abs/1110.5911
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