A new study has unveiled that exoplanets, which are similar to Neptune, have the potential of developing into Earth like habitable planets. The study has been led by the University of Washington (UW) doctoral student Rodrigo Luger and research assistant professor Rory Barnes and has been detailed in the journal Astrobiology. The study authors have explained how these “mini-Neptunes”, as they have been termed, can transform themselves into habitable planets.
Luger said “There are many processes that are negligible on Earth but can affect the habitability of M dwarf planets. Two important ones are strong tidal effects and vigorous stellar activity.” The habitability of these planets depends on the host star, which determines the range and size of its habitable zone, on the basis of the mass and size of the star. The size and mass of these stars, having exoplanets orbiting around, are examined by the astronomers to see if any planet is located in the habitable zone.
Most of the stars which are within the Milky Way Galaxy are M dwarfs having small habitable zones and short range. The planets orbiting them must be close enough so that it remains warm and liquid water can form on the surface to support life. This range is called as Goldilocks zone or habitable zone around the star. Mini-Neptunes could have thick atmospheres and could be located far from their parent star, but with the tidal forces they can get migrated inwards towards their sun. Luger said “They are initially freezing cold, inhospitable worlds. But planets need not always remain in place. Alongside other processes, tidal forces can induce inward planet migration.”
With the migration of these planets, the powerful streams of radiation can push away the thick gases covering the planets resulting in the appearance of habitable evaporated cores. Luger explained “Luckily, on Earth it’s really only the water in the oceans that gets distorted, and only by a few feet. But close-in planets, like those in the habitable zones of M dwarfs, experience much stronger tidal forces.” Increased volcanism can also be the outcome of tidal forces and this might result in the release of large amounts of material into the atmosphere of the exoplanets. This may produce greenhouse effect which would further cause warming of the planet. But, in case the process continues, the oceans of the planet would boil away eliminating possibility of the origin of life. However, to transform into a habitable world, a number of transformations are required in the exoplanets.