TITLE: A Search for Vulcanoids with the STEREO Heliospheric
Imager AUTHORS: A. J. Steffl, N. J. Cunningham, A. B. Shinn, D.
D. Durda, S. A. Stern FIRST AUTHOR’S INSTITUTION: Southwest
Research Institute, Boulder The recent evidence for an asteroid
belt in the Vega system highlights how well we’re getting to
know the solar systems around other stars. But there are some
surprising gaps in our knowledge of our own. Inwards of the
orbit of Mercury, there exists a dynamically stable region
between about 0.21 AU and 0.07 AU where objects can orbit
without being perturbed by Mercury or vaporized by the Sun. As
far back as 1859 astronomers proposed that there might be at
least one small planet lurking in this region, at the time a
potential explanation for the odd precession of Mercury, and
gave this hypothetical world the name “Vulcan”. Although
Mercury’s orbital behavior was later explained by Einstein using
general relativity, the idea of close-in planetesimals called
“Vulcanoids” stuck around. The orbital motions