[BRIEF NOTE] The Problem with Tau Ceti

[rfmcdonald]

Tau Ceti is a star some 11.9 light years away from our Solar System, one of the twenty closest star systems excluding undiscovered solitary brown dwarves. A solitary yellow dwarf--indeed, a prototype of this class of star--Tau Ceti has long featured prominently as a potential home for life, whether human colonial or indigenous. The fact that Tau Ceti is substantially older than our Sol does mean that it has fewer of the heavy elements needed to produce rocky worlds like our own, but conversely the age of the star gives life more time to develop. Tau Ceti seemed attractive.

This changed when astronomers discovered that Tau Ceti's Oort cometary cloud is ten times denser than Sol's. Even if everything was equal, this would suggest that any hypothetical rocky planets orbiting Tau Ceti would be substantially more likely to be targets of devastating cometary impacts. As james_nicoll has pointed out in two postings (1, 2), things are not equal, with two stars--UV Ceti and YZ Ceti--bordering on the fringes of Tau Ceti's Oort cloud, ready to nudge comets into collision courses with planets at a high frequency. Best look elsewhere for the aliens, it seems.