Planet-forming disk could create thousands of oceans

Posted by Kate Taylor

Astronomers have discovered an embryonic solar system surrounded by a cloud of water vapor that could eventually form comets and deliver oceans to dry worlds.

The star TW Hydrae, 176 light years away in the constellation Hydra, is surrounded by enough water to fill Earth's oceans thousands of times over.

It was discovered by researchers using the Heterodyne Instrument for the Far-Infrared (HIFI) on the orbiting Hershel Space Observatory, who detected the chemical signature of water.

"This tells us that the key materials that life needs are present in a system before planets are born," says University of Michigan astronomy professor Ted 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."

While warm water vapor's previously been found in planet-forming disks close to the central star, this is the first time that such a vast quantity has been discovered in the cooler, far reaches of disks where comets and giant planets take shape.

"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," says said principal investigator Michiel Hogerheijde of Leiden University in the Netherlands.

"These would be a prime delivery mechanism for water on planetary bodies."

Comets are believed to have delivered a significant portion of Earth's oceans, with comet Hartley 2 recently found to have the same chemical composition as our oceans.