Did you try this email address ?
[email protected]


Are you can try their Postal address:

Alain Chenciner
IMCCE-Observatoire de Paris
77 Avenue Denfert-Rochereau
F-75014 Paris
France

Richard Montgomery
Department of Mathematics
University of California
Santa Cruz, CA 95064

The closest answer I can get from Internet is :
The orbit persists even when the three masses aren’t precisely the same, and it can survive a tiny disturbance without serious disruption.

"What stability means physically is that there is some chance that the [figure-eight orbit] might actually be seen in some stellar system," Montgomery says. The chance that such a three-body system exists somewhere in the universe, however, is very small. Numerical experiments suggest that the probability is somewhere between one per galaxy and one per universe.
Ref : Orbiting in a figure-eight loop, Science News, Week of Apr. 14, 2001; Vol. 159, No. 15