in the system Beta Pictorius 63 lightyears away there are clouds of carbon monoxide that seem to indicate 2 mars size planets smashing into each other.
Learn more here:
http://www.latimes.com/science/sciencenow/la-sci-sn-beta-pictoris-star-planet-gas-collision-comets-carbon-monoxide-20140307,4290748,2959163.story#axzz2vM3ItsBk