Washington State University researchers have identified 24 top contenders for super habitable exoplanets that would be better at supporting life than the Earth. The exoplanets are all over 100 light-years away. There is now a database of 4500 exoplanets from the ongoing surveys of other stars.
Superhabitable exoplanets have the following features:
* are in the habitable zone of their star. This orbit means that they would have a surface temperature for liquid water.
* Older planets would have more time for life to develop. It took 4 billion years for life to develop on Earth. Superhabitable planets are 5 to 8 billion years old.
* A planet that is 10% larger than the Earth should have more habitable land. One that is about 1.5 times Earth’s mass would be expected to retain its interior heating through radioactive decay longer and would also have a stronger gravity to retain an atmosphere over a longer time period.
* they looked at planets around G type stars that are like our sun but also K dwarf stars. K dwarf stars could keep planets habitable for 20 to 70 billion years because the star burns at a cooler and more sustainable way.
Our telescopes are not good enough to confirm some of the features of these exoplanets. We cannot identify how much land they have. However, new generations of more powerful telescopes will enable better observations. Even the planetary mass estimates are very crude. The 24 candidates were planets that are estimated to have two Earth masses or less. However, the mass estimates are based upon the estimate of radius. The radius are less than 1.6 times the Earth radius.
We still have a lot to learn. We have only just started having telescopes that can identify exoplanets indirectly based upon the gravitational wobbling of the star. An interesting possibility is that a habitable planet might be around 5% of stars and super habitable planets could be around 0.5 to 1.0% of stars.
SOURCES- Washington State University, Astrobiology
Written By Brian Wang, Nextbigfuture.com