Telescopes are currently searching for new world indiscriminately

Nov 30, 2013 08:03 GMT  ·  By

Researchers at the Pennsylvania State University argue in a new study that efforts to detect potentially habitable extrasolar planets around other stars should be conducted in a more conservative manner. That is to say, astronomers should only focus on candidates that show real promise. 

With more than 100 billion stars located in the Milky Way alone, there is no shortage of prospective candidates when it comes to discovering Earth-like rocky exoplanets. But James Kasting, the Evan Pugh professor of geosciences at Penn State, says that not all of them deserve our attention.

He says that a conservative approach to hunting for exoplanets, for example, should not take into account gas giants around other stars at all. Numerous studies conducted over the past few years have revealed the average chances that each type of star has of holding habitable exoplanets.

Therefore, when building new terrestrial planet finders or planet-hunting telescopes, researchers should focus exclusively on stellar types that have a higher chance of allowing for the development of exoplanets in their habitable zones.

A habitable zone is an area around any star where temperatures are just right to support the presence of liquid water on a planet's surface. Too close to the star, and the water would boil off; too far and it will freeze in polar caps and underground, Astrobiology Magazine reports.

Kasting says that future exploration studies should be centered on worlds that feature either a solid or a liquid surface, and which contain liquid water. These planets are the most likely to exhibit the necessary conditions for the development of early life. The presence of an atmosphere is desirable as well, though not necessarily for liquid-surfaced worlds.

“It’s one of the biggest and oldest questions that science has tried to investigate: is there life off the Earth? NASA is pursuing the search for life elsewhere in the Solar System, but some of us think that looking for life on planets around other stars may actually be the best way to answer this question,” the expert says.

A recent study conducted at Penn State revealed that the incidence of potentially habitable worlds around M-class dwarfs is around 0.4 to 0.5. Another study, presented at the Kepler Science Conference in early November, suggests that Sun-like yellow dwarfs have a planetary frequency of 0.22.

By estimating the probabilities of Earth-like exoplanets existing around each type of star, astronomers could become even more effective in their search for habitable worlds. Telescopes such as Kepler are already extremely efficient, but they analyze starlight in bulk, and do not target specific types of stars.