Nearby protoplanetary disk contains enough water for thousands of oceans

Artist's conception of the cloud of water vapour surrounding the star TW Hydrae. Credit: NASA/JPL-Caltech/T. Pyle (SSC/Caltech)

Astronomers have found a nearby protoplanetary disk (where planets are still forming around their star), that contains a lot of water vapour, enough for the equivalent of thousands of oceans. The star, TW Hydrae, is about 176 light-years away in the constellation Hydra. The water was discovered by the orbiting Hershel Space Observatory, and a paper about the finding has been published in the October 21 edition of the journal Science.

“This tells us that the key materials that life needs are present in a system before planets are born,” said Bergin, a HIFI co-investigator. “We expected this to be the case, but now we know it is because have directly detected it. We can see it.”

Water vapour has been found in other protoplanetary systems before, but this is the first evidence for vast quantities which extend into the cooler outer reaches of the disk, where gas giant planets and comets typically form. Comets are thought to have delivered water and organics to the early Earth through impacts, so a similar process could happen in other solar systems as well, increasing the chances for habitable planets.

“The detection of water sticking to dust grains throughout the planet-forming disk would be similar to events in our own solar system’s evolution, where over millions of years, these dust grains would then coalesce to form comets. These would be a prime delivery mechanism for water on planetary bodies,” said principal investigator Michiel Hogerheijde of Leiden University in the Netherlands.

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