Recent collisional jet from a primitive asteroid
  Here we show an example of a young asteroid cluster located in a dynamically stable region, which was produced by partial disruption of a primitive body about 30 km in size. We estimate its age to be only 1.9 +/- 0.3 Myr, thus its post-impact evolution should have been very limited. The large difference in size between the largest object and the other cluster members means that this was a cratering event. The parent body had a large orbital inclination, and was subject to collisions with typical impact speeds higher by a factor of 2 than in the most common situations encountered in the main belt. For the first time we have at disposal the observable outcome of a very recent event to study high-speed collisions involving primitive asteroids, providing very useful constraints to numerical simulations of these events and to laboratory experiments. 
Bojan Novakovic, Aldo Dell'Oro, Alberto Cellino, Zoran Knezevic
astro-ph.EP physics.space-ph