The ongoing discoveries of extrasolar planets are unveiling a wide range of terrestrial mass ( size ) planets around their host stars .
In this letter , we present estimates of habitable zones ( HZs ) around stars with stellar effective temperatures in the range 2600 K - 7200 K , for planetary masses between 0.1 M _ { \oplus } and 5 M _ { \oplus } .
Assuming { H _ { 2 } O } - ( inner HZ ) and { CO _ { 2 } } - ( outer HZ ) dominated atmospheres , and scaling the background N _ { 2 } atmospheric pressure with the radius of the planet , our results indicate that larger planets have wider HZs than do smaller ones .
Specifically , with the assumption that smaller planets will have less dense atmospheres , the inner edge of the HZ ( “runaway greenhouse” limit ) moves outward ( \sim 10 \% lower than Earth flux ) for low mass planets due to larger greenhouse effect arising from the increased { H _ { 2 } O } column depth .
For larger planets , the { H _ { 2 } O } column depth is smaller , and higher temperatures are needed before water vapor completely dominates the outgoing longwave radiation .
Hence the inner edge moves inward ( \sim 7 \% higher than Earth ’ s flux ) .
The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo .
New , 3-D climate model results from other groups are also summarized , and we argue that further , independent studies are needed to verify their predictions .
Combined with our previous work , the results presented here provide refined estimates of HZs around main-sequence stars and provide a step towards a more comprehensive analysis of HZs .