Water Discovered On Asteroid 170 Light Years Away: Could A Habitable Planet Have Been Found Beyond The Solar System?
For the first time ever, astrophysicists have found evidence of a water-rich, rocky asteroid beyond the confines of our solar system. Scientists from two English universities say that dust and debris surrounding white dwarf GD 61, which lies some 170 light years away, have oxygen signatures which indicate that they originated from a large body containing 26 percent water by mass. The findings appear today in the journal Science.
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While evidence of water outside of our solar system has been found before, this is the first time water evidence has been found on a rocky body. According to study co-author Boris Gänsicke of the University of Warwick in England, the presence of both a rocky surface and water is "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."
The scientists based their findings on observations from the Hubble Space Telescope and a telescope at Hawaii's Keck Observatory. The telescope data allowed researchers to identify chemicals in the layers of white dwarfs like GD 61. Although twelve broken-up exoplanets orbiting white dwarves have been studied in this way, this is the first to show water evidence.
"The finding of water in a large asteroid means the building blocks of habitable planets existed -- and maybe still exist -- in the GD 61 system, and likely also around substantial number of similar parent stars," said study lead author Jay Farihi, of the University of Cambridge. "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 GD 61 had the ingredients to deliver lots of water to their surfaces."
Farihi said that the water-rich debris shows that there was "definitely potential for habitable planets in this exoplanetary system." Not only did this potentially habitable planet have water, but there was a ton of it: compare the GD 61 system's 26 percent water by mass to Earth's water mass of only 0.02 percent.
Not everyone is so quick to agree with Farihi and his team that the oxygen in the GD 61 system is evidence that water existed. Claire Moutou, an exoplanet specialist at the Laboratory of Astrophysics of Marseille in France, told Scientific American that she finds "the analysis/conclusions of the paper reasonable, as far as the amount of oxygen available to lie in H2O molecules is concerned. The interpretation of the origin of this water content is more speculative." Lisa Kaltenegger of Harvard University and the Max Planck Institute for Astronomy in Germany only went so far as to say that the possibility of an inventory of water was "a very interesting scientific question still under investigation."
In addition to the water possibility, one of the interesting things about GD 61 is that it may show the same path that our sun will take. The star GD 61 became a red giant before dying out 200 million years ago; in its present state, it's a white dwarf. In about five billion years, our sun is expected to become a red giant and then burn out too. Will we survive when that happens? According to Farihi, Mercury and Venus will burn up, but Earth may make it through.
"Most theorists believe the Earth will survive," said Farihi. Life, however, will not: the planet will become uninhabitably hot. But Mars will survive, so perhaps it really is a good idea to start colonizing the Red Planet.
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