Supersonic `rain on young star system to shed light on planet formation

There is enough water vapour in a star system forming in space to fill Earths oceans five times, besides shedding light on planet formation, claim NASA astronomers.

Washington, Aug.30 : There is enough water vapour in a star system forming in space to fill Earth's oceans five times, besides shedding light on planet formation, claim NASA astronomers.

This finding has been revealed through the use of NASA's Spitzer Space Telescope, which concludes that water vapour is pouring down from the young star system's natal cloud and smacking into a dusty disk where planets are thought to form.The observations provide the first direct look at how water, an essential ingredient for life as we know it, begins to make its way into planets, possibly even rocky ones like our own."For the first time, we are seeing water being delivered to the region where planets will most likely form," said Dan Watson of the University of Rochester, New York.

Watson, the lead author of a paper about this "steamy" young star system, which appears in today's issue of Nature, identifies it as NGC 1333-IRAS 4B, and says that it is still growing inside a cool cocoon of gas and dust.

Within this cocoon, circling around the embryonic star, is a burgeoning, warm disk of planet-forming materials.

Watson and his colleagues studied 30 of the youngest known stellar embryos using Spitzer's infrared spectrograph, an instrument that splits infrared light open into a rainbow of wavelengths, revealing "fingerprints" of molecules.

Of the 30 stellar embryos, they found only one, NGC 1333-IRAS 4B, with a whopping signature of water vapour.

This vapour is readily detectable by Spitzer, because as ice hits the stellar embryo's planet-forming disk, it heats up very rapidly and glows with infrared light.

Astronomers like Michael Werner, a project scientist for the Spitzer mission at NASA's Jet Propulsion Laboratory in Pasadena, California say they have captured a unique phase of a young star's evolution, when the stuff of life is moving dynamically into an environment where planets could form.

The new Spitzer data indicate that ice from the stellar embryo's outer cocoon is falling toward the forming star and vaporizing as it hits the disk.

Water is abundant throughout our universe. It has been detected in the form of ice or gas around various types of stars, in the space between stars, and recently Spitzer picked up the first clear signature of water vapour on a hot, gas planet outside our solar system, named HD 189733b.

In the new Spitzer study, water also serves as an important tool for studying long-sought details of the planet formation process.

By analysing what's happening to the water in NGC 1333-IRAS 4B, the astronomers are learning about its disk.

"Water is easier to detect than other molecules, so we can use it as a probe to look at more brand-new disks and study their physics and chemistry. This will teach us a lot about how planets form," claims Watson.

ANI