Phoenix Planets

"...Qualsiasi Creatura dell'Universo la quale sia tanto evoluta da riuscire a raggiungere il nostro Pianeta, coprendo distanze che sono difficili da cogliere anche alla nostra immaginazione, deve essere altrettanto saggia da capire - dopo averci trovati - che è meglio starsene lontana da noi..."

(dalla serie televisiva "CSI")

Caption originale: This artist's concept depicts a type of dead star called pulsar and the surrounding disk of rubble discovered by NASA's SST. The pulsar, called 4U 0142+61, was once a massive star until about 100.000 years ago when it blew up in a supernova explosion and scattered dusty debris into space. Some of that debris was captured into what astronomers refer to as a "fallback disk", now circling the remaining stellar core, or pulsar. The disk resembles protoplanetary disks around young stars, out of which planets are thought to be born.
Supernovas are a source of Iron, Nitrogen and other heavy metals in the universe. They spray these elements out into space, where they eventually come together in clouds that give rise to new stars and planets. The Spitzer finding demonstrates that supernovas might also contribute heavy metals to their own planets, a possibility that was first suggested when astronomers discovered planets circling a pulsar called PSR B1257+12 in 1992.