The Instability of Venus Trojans

Using Laskar's frequency map analysis, we investigate the long-term stability of Venus Trojan orbits. By measuring the diffusion rate of proper frequencies, we outline in phase space the most stable region. It is located between 5° and 10° in proper inclination with libration amplitudes ranging from 50° to 110°. The proper eccentricity is lower than 0.13. The stable region is surrounded by secular resonances that destabilize orbits on short timescales. The dynamical half-life of orbits within the stable region is about 6×108 yr. The Yarkovsky effect further reduces the dynamical lifetime. Therefore, primordial Venus Trojans, if any, cannot have survived until the present. Transient Trojans, on the other hand, cannot be excluded.