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A total of 24 “super-habitable” planets may have more suitable conditions for life than Earth and better stars than the Sun, according to the researchers.
The study, led by Washington State University, identified planets that were older, slightly larger, warmer, and wetter than Earth.
They added that life could thrive more easily on planets orbiting changing stars with a longer lifespan than the sun at a slower rate.
The planets selected by the researchers are said to have better stars than the Sun.
The 24 identified planets are more than 100 light years apart, which means they are difficult to see up close.
However, the researchers have said that these findings could help inform future observations of the telescope.
One of the principal investigators, Professor Dirk Schulze-Makuch, said: “With the next space telescopes, we will get more information, so it is important to select some targets.”
“We have to focus on certain planets that have the most promising conditions for complex life.”
The astronomers created a “superhabitability criterion”, which they used against 4,500 known exoplanets.
Habitability was not defined as definitive signs of life, but rather meant that the conditions necessary for life to flourish were present.
The team analyzed systems with G stars that have a short lifespan of less than 10 billion years, similar to our sun, as well as systems with K dwarf stars.
K-dwarf stars are much smaller and cooler, with lifespan ranging from 20 billion to 70 billion years. This means that orbiting planets may be older, allowing life to advance as much as it has on Earth.
The Earth is currently estimated to be 4.5 billion years old, however researchers argue that a planet between 5,000 and 8 billion years old can support life well.
The team looked for planets around 10% larger than Earth, as this would mean there is likely more habitable land.
These planets could help focus future telescopic observations
They also wanted to have a greater mass, as this would allow the planet to keep its internal heating retained for longer, as well as having a stronger gravity to retain the atmosphere for a longer period of time.
Water was also another key feature identified, with a little more of Earth being sought on super-habitable planets.
A higher surface temperature, about 5 ° C warmer than Earth’s, was also considered better for life.
None of the 24 identified planets met all the criteria, however there is one that meets four of the critical characteristics, meaning it may be more comfortable for life than Earth.
Professor Dirk Schulze-Makuch said: “Sometimes it is difficult to convey this principle of super-habitable planets because we think we have the best planet.
“We have a large number of complex and diverse life forms, and many that can survive in extreme environments. It is good to have an adaptable life, but that does not mean that we have the best of everything.”
The research has been published in Astrobiology.
