THE EFFECTS OF POST-MAIN-SEQUENCE SOLAR MASS-LOSS ON THE STABILITY OFOUR PLANETARY SYSTEM

We present the results of extensive long-term integrations of systems of planets with orbits initially identical to subsets of the planets w ithin our Solar System, but with the Sun's mass decreased relative to the masses of the planets, For systems based on the giant planets, we find an approximate power-law correlation between the time elapsed unt il a pair of planetary orbits cross and the solar-to-planetary-mass ra tio, provided that this ratio is less than or similar to 0.4 times its current value, However, deviations from this relationship at larger r atios suggest that this correlation may not be useful in predicting th e lifetime of the current system. Detailed simulations of the evolutio n of planetary orbits through the solar mass loss phase at the end of the Sun's main-sequence lifetime suggest that the orbits of those terr estrial planets that survive the Sun's red giant phase are likely to r emain stable for (possibly much) longer than a billion years and those of the giant planets are likely to remain stable for (possibly much) more than ten billion years. Pluto is likely to escape from its curren t 2:3 mean-motion resonance with Neptune within a few billion years be yond the Sun's main sequence lifetime if subject only to gravitational forces; its prognosis is likely to be even poorer when nongravitation al forces are included. Implications for the effects of stellar mass l oss on the stability of other planetary systems are discussed. (C) 199 8 Academic Press.