Searching For Vulcanoids

Vulcanoids are a hypothesized population of small asteroid-like bodies in orbits interior to that of Mercury. Their presence or absence would be an important test of cosmogonical theories. There are significant dynamical and thermodynamical constraints that restrict the search area roughly to the ecliptic in the range of 0.1 to 0.25 AU from the Sun. Previous searches rule out only bodies with radii greater than about 50--100 km. We estimate that with current technology a search with a limiting magnitude of 6 at 3.5 microns might be feasible. This limiting magnitude corresponds approximately to the smallest (1 km) objects expected to have survived in this region over the age of the solar system. If such a search were carried out, even the absence of detections would yield definitive results.