Terraformed Exoplanets and SETI

Martin Beech

A brief review is made of the 6 presently known exoplanetary systems with parent stars having ages within 1 percent of their main sequence life time limit. The exoplanets discussed range in mass from 0.05 to 7.4 times that of Jupiter and they move along moderately circular orbits - although 2 have relatively high eccentricities of order 0.4. Three of the systems are known to allow stable orbits within their habitable zone. It is argued that should these, and similar such systems yet to be discovered, support advanced civilizations then their existence might be betrayed through the presence of terraformed (that is engineered) habitable planets situated outside of the canonical habitable region.

Keywords: Planets: stable orbits, exosolar, terraforming, habitable zone, Stars: main sequence lifetime