Astronomy professors from the University of Washington (UW) were able to devise a way to help experts determine which among the exoplanets should be given utmost investigative priority in terms of looking for potential life. Dubbed as "Habitability Index for Transiting Planets," this ranking is said to systematize the study of hundreds of so-called "earth-like" planets.

The conventional way of analyzing the habitable zone or Goldilocks zone of a star is by looking if planets rotate within an area of space that has adequate atmospheric pressure to contain surface liquid water. Possessing this feature may mean that life can be supported in the said planet.

In the new study, astronomers are empowered to see past beyond the standard parameters and consider studying other habitability factors more comprehensively.

The new index projects the extent of "rockiness" that a planet has and takes into consideration its "eccentricity-albedo degeneracy," which balances the amount of energy that a planet emulates from its surface versus the circularity of its orbit. The latter affects the energy level that the planet receives from the star it rotates.

The researchers said that both eccentricity and albedo oppose one another but having the correct equilibrium between them can generate a life-supporting energy balance that makes a planet habitable. With this, it is said that the most habitable planets are those that receive about 60-90 percent of the solar radiation that Earth gets from the sun.

The criteria in the said energy phenomenon are highlighted in the newly-formed index, which then enables astronomers to have a quick basis for study.

Rory Barnes, one of the study authors from UW's Virtual Planetary Laboratory, said that the team has basically created a method to collate all the available observational information and formulate a prioritization design.

With the emergence of more powerful telescopes, this index may truly come in handy. Barnes commented that as the world treads to a time when hundreds of exoplanets are already discovered and are placed in the list of potential study foci, experts may now be able to say, "OK, that's the one we want to start with."

"The power of the habitability index will grow as we learn more about exoplanets from both observations and theory," Barnes closed.

The paper written by Barnes together with fellow UW professor Victoria Meadows and research assistant Nicole Evans, has been accepted for publication in Astrophysical Journal. 

Photo: Rory Barnes

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