Tides may turn habitable planets into hothouses
London: Scientists say tides may dry out what would otherwise be habitable planets around small stars, making them hostile to life.
Rory Barnes of the University of Washington in Seattle and his colleagues examined what would happen to Earth-like planets orbiting the most common type of star in the galaxy: red dwarfs.
These stars are much cooler and fainter than the sun, suggesting that the habitable zones around them - in which planets can have liquid water on their surface - are much closer in.
So, any planets orbiting in those zones feel very strong gravitational tugs from the star, the New Scientist reported.
The star’s pull squeezes and stretches the planet, heating it up.
The researchers found that stars with a mass less than a third of that of our sun have habitable zones so close in that this tidal heating would evaporate any planet's water.
Light from the planet’s star would then split the water vapour into hydrogen, which would escape into space, and oxygen, which could go on to form the greenhouse gas carbon dioxide.
Planets blanketed in CO2 would heat up further, developing into uninhabitable hothouses like Venus, the team concluded.