The new study by scientists at the Universities of Warwick and Cambridge, analyzed the dust and debris surrounding the white dwarf star GD 61 170 light-years away.
Using observations obtained with the Hubble Space Telescope and the large telescopes of the W. M. Keck Observatory, they found an excess of oxygen -- a chemical signature that indicates that the debris had once been part of a bigger body originally composed of 26 percent water by mass.
By contrast, only approximately 0.023 percent 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.
We know from our own solar system that the dwarf planet Ceres contains ice buried beneath an outer crust, and the researchers draw a parallel between the two bodies. Scientists believe that bodies like Ceres were the source of the bulk of our own water on Earth.
The researchers suggest it is most likely that the water detected around the white dwarf GD 61 came from a minor planet at least 90 km in diameter but potentially much bigger, that once orbited the parent star before it became a white dwarf.
Like Ceres, 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 90 km [60 miles].
"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," Lead author Jay Farihi, from Cambridge's Institute of Astronomy, said.
"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.
"Our results demonstrate that there was definitely potential for habitable planets in this exoplanetary system," Farihi said.
The study is published in the journal Science.
--ANI (Posted on 11-10-2013)