Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$   Pictoris Debris Disk
  Many stars are surrounded by disks of dusty debris formed in the collisions of asteroids, comets and dwarf planets. But is gas also released in such events? Observations at submm wavelengths of the archetypal debris disk around $\beta$ Pictoris show that 0.3% of a Moon mass of carbon monoxide orbits in its debris belt. The gas distribution is highly asymmetric, with 30% found in a single clump 85AU from the star, in a plane closely aligned with the orbit of the inner planet, $\beta$ Pic b. This gas clump delineates a region of enhanced collisions, either from a mean motion resonance with an unseen giant planet, or from the remnants of a collision of Mars-mass planets. 
W.R.F. Dent, M.C. Wyatt, A. Roberge, J.-C. Augereau, S. Casassus, S.   Corder, J.S. Greaves, I. de Gregorio-Monsalvo, A. Hal...
astro-ph.SR