The YORP Effect Can Efficiently Destroy 100 Kilometer Planetesimals At The Inner Edge Of The Solar System

The Vulcanoids are a population of suspected asteroids that are predicted to be located between the Sun and Mercury at distances of 0.05-0.25 AU. The Vulcanoids are of interest because they would occupy apparently stable orbits, which are often occupied by exoplanets in other star systems. Searches for the Vulcanoids have been carried out but these searches have always been unsuccessful in finding any trace of them. Here, we test the hypothesis that YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect is responsible for the destruction of Vulcanoids into small fragments which are then rapidly transported by the Yarkovsky effect out of the Vulcanoid region. The YORP effect spins/down up asteroids due to the radiation of thermal energy from an asymmetrical figure, whereas the Yarkovsky effect shrinks/grows the heliocentric orbit due to an imbalance of thermal radiation from the evening side relative to the dawn side of the asteroid. The YORP effect destroys Vulcanoids by spinning them up so fast that the gravitational accelerations holding components of the body together are matched by centrifugal accelerations, this causes the body to rotationally fission. i.e break apart. We calculated the timescale of this fission process for a parent Vulcanoid and for each of their subsequent generational fragments. We show that objects with radii up to 100 kilometers in size are efficiently destroyed by the YORP effect doing so in a timescale that is much younger than the age of the Solar System. For these preliminary calculations, we have made the assumption that after fission of the parent, the two remaining children are the same in mass and radius. Different assumptions for child mass and size after fission of the parent will be determined later, thus changing the total time scales based upon the different parent to child ratios.