Stars with Dusty Disks May Harbor Earth-like Alien Planets

According to researchers stars with disks of debris around them might be good targets to search for Earth-like alien planets.

A few hundred stars have been found that show signs of a debris disk by astrophysicists of the Observatory of Bordeaux in France. The lifetime of dust is very short compared with that of stars, for instance, the dust can get scattered out into interstellar space by gravitational perturbations from giant planets. It is thought that any debris disks astronomers spot are replenished by collisions between asteroid-sized bodies that are basically leftovers of rocky planet formation. As such, if any disk that is seen is relatively large, its system might be calm enough in terms of its orbital dynamics for rocky worlds to form. According to astrophysicist Sean Raymond of the Observatory of Bordeaux in France for debris disks to exist around old stars, you need a dynamically calm environment without strong gravitational perturbations. To form terrestrial planets, you need the same thing. So, it makes sense that these two outcomes should be correlated. To explore this idea, Raymond and his colleagues simulated how planets emerge from debris disks. Although Raymond proposes that stars with debris disks should be good places to look for terrestrial planets, it turns out only about one in six stars older than 1 billion years are observed to have debris disks. As said Raymond the fact that many stars apparently do not have debris disks probably means that lots of stars simply aren’t born with enough material to make debris disks. It’s hard to say anything about a specific star with no debris disk, although statistically speaking, it may have terrestrial planets. But a star with a debris disk, according to Raymond, has a high probability of hosting terrestrial planets, and if it also doesn’t have an eccentric giant planet, the probability is even higher.