11Oct2012

Water Discovered In Collapsing Molecular Cloud.

Herschel’s infrared view of part of the Taurus Molecular Cloud, within which the bright, cold pre-stellar cloud L1544 can be seen at the lower left. Credits: ESA/Herschel/SPIRE

 Water, water, everywhere… and not a drop to drink. Unless, of course, you’re into giant molecular clouds!If we want to find life out there’ we need to find water.

Thanks to new observations done with ESA’s Herschel Space Observatory, astronomers have now located enough water vapor to fill Earth’s oceans 2000 times over. A giant pool? No. It’s contained in a gas and dust cloud that stands at the edge of collapsing into a new, Sun-like star. In the depths of space, stars form from cold, dark clouds of gas and dust known as “pre-stellar cores”. These regions contain all the necessary ingredients to form solar systems much like our own.

While water has been discovered outside our Solar System, these samples of gas and ice are deposited on dust grains found near star forming regions and in proto-planetary discs. The latest discovery of a massive amount of water came from Herschel observations of a pre-stellar core located in the constellation of Taurus in a region known as Lynds 1544. This is the first time water vapor has been detected in a molecular cloud ready to collapse. The water vapor has been released from the icy dust grains by high energy cosmic rays.

“To produce that amount of vapor, there must be a lot of water ice in the cloud, more than three million frozen Earth oceans’ worth,” says Paola Caselli from the University of Leeds, UK, lead author of the paper reporting the results in Astrophysical Journal Letters.

“Before our observations, the understanding was that all the water was frozen onto dust grains because it was too cold to be in the gas phase and so we could not measure it.

“Now we will need to review our understanding of the chemical processes in this dense region and, in particular, the importance of cosmic rays to maintain some amount of water vapor.”

And just what direction is the water flowing? In this case it’s headed towards the core of the cloud where a new star could eventually form. This clues researchers that gravitational collapse is in its beginning phases.

“There is absolutely no sign of stars in this dark cloud today, but by looking at the water molecules, we can see evidence of motion inside the region that can be understood as collapse of the whole cloud towards the center,” says Dr. Caselli.

“There is enough material to form a star at least as massive as our Sun, which means it could also be forming a planetary system, possibly one like ours.”

Close-up of L1544 with the water spectrum seen by Herschel, taken from the centre of the pre-stellar core. Credits: ESA/Herschel/SPIRE/HIFI/Caselli et al.

This discovery of a huge amount of water vapor is quite exciting. While a certain portion of the water detected in L1544 will be incorporated into the star’s formation, a substantial portion will remain in the surrounding disc, providing a wet reservoir capable of feeding new planets with the life-giving substance.

“Thanks to Herschel, we can now follow the ‘water trail’ from a molecular cloud in the interstellar medium, through the star formation process, to a planet like Earth where water is a crucial ingredient for life,” says ESA’s Herschel project scientist, Göran Pilbratt.

Original Story Source: ESA Space Science News. Submitted by Tammy Plotner for “Dave Reneke’s World of Space and Astronomy News”.

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