A Venus-like exoplanet may have atmosphere with oxygen but not life, researchers report, adding that their magma ocean-atmosphere model can help solve the puzzle of how Venus evolved over time.
The distant planet GJ 1132b is located 39 light-years from Earth. It might have an atmosphere despite being baked to a temperature of around 450 degrees Fahrenheit.
“This planet might be the first time we detect oxygen on a rocky planet outside the solar system,” said study co-author Robin Wordsworth from Harvard Paulson School of Engineering and Applied Sciences.
Astronomer Laura Schaefer from Harvard-Smithsonian Center for Astrophysics and her colleagues examined the question of what would happen to GJ 1132b over time if it began with a steamy, water-rich atmosphere.
Orbiting so close to its star at a distance of just 1.4 million miles the planet is flooded with ultraviolet light. UV light breaks apart water molecules into hydrogen and oxygen, both of which then can be lost into space.
However, since hydrogen is lighter it escapes more readily, while oxygen lingers behind.
“On cooler planets, oxygen could be a sign of alien life and habitability. But on a hot planet like GJ 1132b, it’s a sign of the exact opposite - a planet that’s being baked and sterilised,” said Schaefer in a statement.
Since water vapour is a greenhouse gas, the planet would have a strong greenhouse effect, amplifying the star’s already intense heat. As a result, its surface could stay molten for millions of years.
If any oxygen does still cling to GJ 1132b, next-generation telescopes like the Giant Magellan Telescope and James Webb Space Telescope may be able to detect and analyse it.
Venus probably began with Earth-like amounts of water, which would have been broken apart by sunlight.
Yet it shows few signs of lingering oxygen. The missing oxygen problem continues to baffle astronomers.
