Co-orbital Asteroids as the Source of Venus's Zodiacal Dust Ring

Photometry from the Helios and STEREO spacecraft revealed regions of enhanced sky surface-brightness suggesting a narrow circumsolar ring of dust associated with Venus's orbit. We model this phenomenon by integrating the orbits of 10,000,000+ dust particles subject to gravitational and non-gravitational forces, considering several different kinds of plausible dust sources. We find that only particles from a hypothetical population of Venus co-orbital asteroids can produce enough signal in a narrow ring to match the observations. Previous works had suggested such objects would be dynamically unstable. However, we re-examined the stability of asteroids in 1:1 resonance with Venus and found that ~8% should survive for the age of the solar system, enough to supply the observed ring.

Currently five Venus co-orbitals are known where each of them is in the Earth crossing region. Our analysis shows that a few percent of our hypothetical Venus co-orbitals can stay in the 1:1 mean-motion resonance with Venus while their orbital eccentricity is gradually increased up to the point where their orbits start crossing Earth's orbit. We suggest that the Venus co-orbitals observed today are dynamically evolved cousins of a yet unobserved low eccentricity low inclination population of asteroids co-orbiting with Venus.