How water forms where Earth-like planets are born

Dec 17, 2009

(PhysOrg.com) -- In a study that helps to explain the origins of water on Earth, University of Michigan astronomers have found that water vapor can form spontaneously in habitable zones of solar systems, and that it develops into a protective layer that shields other water and organic molecules from harmful stellar radiation.

Organic molecules such as sugars and amino acids are the precursors to life.

The findings are published in the Dec. 18 edition of Science.

"When you're close to a star, the radiation is destructive to most molecules. But we were able to prove that water could form quickly enough to shield itself and other molecules from that radiation," said Ted Bergin, an associate professor in the Department of Astronomy.

Bergin and Thomas Bethell, a postdoctoral astronomy researcher, conducted a computational analysis to come to this conclusion.

They determined that the series of necessary for water vapor to be created are only activated at temperatures higher than 300 degrees Kelvin (which is about 80 degrees Fahrenheit.) These temperatures are only present relatively close to a star—in the areas where terrestrial planets such as Earth would form. Out farther, at Jupiter's distance, the gasses are too cold for water vapor to form.

Once the water vapor starts to form, the scientists found, it forms fast enough to build a shell similar to Earth's ozone layer, which acts like an umbrella to protect the life below it from . Not only does this astronomical "ozone layer" of water vapor protect other water molecules behind it, it would also shelter organic molecules.

"There's a rich organic chemistry that precedes the birth of stars," Bergin said. "It's simpler, but similar to the chemistry of life. The behavior of water can allow that chemistry to proceed. Without the protection water vapor provides, those organic molecules would be destroyed."

Conceivably, some of this water and organic matter could be incorporated into nascent, Earth-like worlds.

The paper is called "Formation and Survival of in the Terrestrial Planet-Forming Region." This research is funded by NASA.

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thorargent
not rated yet Dec 21, 2009
While this is interesting, it seems that the most important mechanism has been overlooked. Most water would form inside the planets themselves. The incorporation of ammonia and methane into the materials due in part to the presence of water would then lead to the making of oceans. Lava in contact with ammonia will produce water vapor and nitrogen gas, methane in the same conditions will produce higher order alkanes and water vapor as well as carbon dioxide and graphite. The newly formed water will dissolve salts, silica, and metals and produce salt domes, quartz veins, native metal deposits, and the atmosphere and oceans.

So while this is interesting, it is only a small part of the actual creation of water.