A Possible Massive Asteroid Belt around ζ Leporis

Abstract

We have used the Keck I telescope to image at 11.7 and 17.9 μm the dust emission around ζ Leporis, a main-sequence A-type star at 21.5 pc from the Sun with an infrared excess. The excess is at most marginally resolved at 17.9 μm. The dust distance from the star is probably <=6 AU, although some dust may extend to 9 AU. The mass of observed dust is ~10²² g. Since the lifetime of dust particles is about 10⁴ yr because of the Poynting-Robertson effect, we robustly estimate at least 4×10²⁶ g must reside in parent bodies, which may be asteroids if the system is in a steady state and has an age of ~300 Myr. This mass is approximately 200 times that contained within the main asteroid belt in our solar system.