Julia Fang, Jean-Luc Margot
We investigate the Kozai mechanism in the context of near-Earth binaries and
the Sun. The Kozai effect can lead to changes in eccentricity and inclination
of the binary orbit, but it can be weakened or completely suppressed by other
sources of pericenter precession, such as the oblateness of the primary body.
Through numerical integrations including primary oblateness and 3 bodies (the
two binary components and the Sun), we show that Kozai cycles cannot occur for
the closely-separated near-Earth binaries in our sample. We demonstrate that
this is due to pericenter precession around the oblate primary, even for very
small oblateness values. Since the majority of observed near-Earth binaries are
not well-separated, we predict that Kozai cycles do not play an important role
in the orbital evolution of most near-Earth binaries. For a hypothetical wide
binary modeled after 1998 ST27, the separation is large at 16 primary radii and
so the orbital effects of primary oblateness are lessened. For this wide
binary, we illustrate the possible excursions in eccentricity and inclination
due to Kozai cycles as well as depict stable orientations for the binary's
orbital plane. Unstable orientations lead to collisions between binary
components, and we suggest that the Kozai effect acting in wide binaries may be
a route to the formation of near-Earth contact binaries.
View original:
http://arxiv.org/abs/1111.3046
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