Recipe for Habitable Planets Revealed in New Study

Some seemingly adverse events in space may actually make Neptune-like planets habitable, research suggest.

A study by researchers from Washington University argues that habitable worlds may haves started off as mini-Neptunes which are massive planets with solid core and thick hydrogen atmosphere existing far away from their stars. The research claims that such planets could become habitable when they come in to the habitable zone of M dwarfs, stars smaller and dimmer than the Sun, Discovery News reported. M dwarfs have smaller habitable zones, distance from a star where life can take form on a planet.

"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," said Rodrigo Luger one of study's authors, in a news release.

The strong tidal forces exerted by the star tug on the planet, changing its shape and also drawing it close. Tidal forces exerted by the Sun and Moon cause ocean tides on Earth. However planets which are closer to M dwarfs could heat the planet and create volcanism. Stellar activity created by radiation can destroy atmosphere and heat the planet causing a greenhouse effect.

However Neptune-like planets have icy cores with atmosphere of hydrogen. Tidal forces from M dwarfs can draw such planets closer into habitable zone. Stellar activity can rid the planet of hydrogen atmosphere and cause formation of oceans, giving life a chance.

Tidal force and stellar activity are required conditions but not sufficient.

"The bottom line is that this process - the transformation of a mini-Neptune into an Earthlike world - could be a pathway to the formation of habitable worlds around M dwarf stars," Luger said.