Jeffrey J. Sudol, Nader Haghighipour
Debates regarding the age and inclination of the planetary system orbiting
the star HR 8799 and the recent release of additional astrometric data prompted
us to carry out a series of dynamical simulations of this system at several
different inclinations for planetary masses of 7-10-10-10 MJup. We find the
longest system lifetimes are less than ~5 Myr at inclinations of 0{\deg} and
13{\deg}, and ~41, ~46, and ~31 Myr at 18{\deg}, 23{\deg}, and 30{\deg},
respectively. Given such short dynamical lifetimes, and considering the
location of the system on the age-luminosity diagram for low-mass objects, the
most reasonable conclusion is that the planetary masses are less than
7-10-10-10 MJup and the system is quite young. We do find, however, one model
at i=30{\deg} that remains stable for ~155 Myr, permitting an older system with
higher mass planets. Although the chi-squared statistics for this model are
marginal, at best, we are not inclined to reject it because of the potential
for systematic differences between the astrometric data obtained with different
instruments. Furthermore, we constrained the orbital elements of the planets to
their astrometric coordinates from one particular instrument at a single epoch,
and we assumed the orbits of the planets to be coplanar. The interesting trend
to note from our simulations is that the coordinates for planet e in the most
stable models tend to be closer to the star than the observed coordinates. We
present the details of our models and discuss the implications of the results.
View original:
http://arxiv.org/abs/1201.0561
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