Midland astrophysicists have found the first evidence of a water-rich rocky planet 170 light years away – a possible step closer to finding life elsewhere in the Universe.
A new study by scientists at the University of Warwick made the finding – the first time water has been found in an Earth-like body outside our solar system – by analysing the dust and debris surrounding the white dwarf star GD61.
Working with counterparts at Cambridge University, they used observations from the Hubble Space Telescope examine the asteroid and found an excess of oxygen.
Analysis indicated that the debris had once been part of a bigger body originally composed of 26 per cent water by mass. By contrast, only approximately 0.023 per cent of the Earth’s mass is water.
Evidence for water outside our solar system has previously been found in the atmosphere of gas giants, but this study marks the first time it has been pinpointed in a rocky body, making it of significant interest in our understanding of the formation and evolution of habitable planets and life.
Professor Boris Gänsicke of the Department of Physics at the University of Warwick said: “At this stage in its existence, all that remains of this rocky body is simply dust and debris that has been pulled into the orbit of its dying parent star.
“However this planetary graveyard swirling around the embers of its parent star is a rich source of information about its former life.
“In these remnants lie chemical clues which point towards a previous existence as a water-rich terrestrial body.
“Those two ingredients – a rocky surface and water – are key in the hunt for habitable planets outside our solar system so it’s very exciting to find them together for the first time outside our solar system.”
White dwarfs are very dense, so while GD61 is similar in diameter to earth, it has a mass roughly that of the sun. A teaspoon of it is estimated to weigh about 5.5 tons.
While that may not sound hospitable, research from our own solar system show like planets have similar ice buried beneath an outer crust. The researchers, in a study published in the journal Science, found the remains came from an asteroid that was ripped apart by the distant white dwarf star 200 million years ago.
They say the water was most likely in the form of ice below the planet’s surface. From the amount of rocks and water detected in the outer envelope of the white dwarf, the researchers estimate that the disrupted planetary body had a diameter of at least 55 miles – but thought to be far more.
It is likely that the object was as large as Vesta, the largest minor planet in the solar system. In its former life, GD61 was a star somewhat bigger than our Sun, and host to a planetary system.
Lead author Jay Farihi, from Cambridge’s Institute of Astronomy, said: “The finding of water in a large asteroid means the building blocks of habitable planets existed – and maybe still exist – in the GD61 system, and likely also around substantial number of similar parent stars.
“These water-rich building blocks, and the terrestrial planets they build, may in fact be common – a system cannot create things as big as asteroids and avoid building planets, and GD61 had the ingredients to deliver lots of water to their surfaces,” Dr Farihi said.
“Our results demonstrate that there was definitely potential for habitable planets in this exoplanetary system.”
Researchers used ultraviolet equipment to analyse, studying the interaction between matter and radiated energy.
As the atmosphere of the Earth blocks the ultraviolet light, such study can only be carried out from space.
The team has observed 12 destroyed exoplanets orbiting white dwarves so far, but this is the first time the signature of water has been found.