Water-soaked planet-forming region near star seen

WASHINGTON (Reuters) - Scientists looking at a fledgling solar system have observed for the first time how water, considered a necessary ingredient for life, begins to make its way to newly forming planets.

They peered at an embryonic star called IRAS 4B located in our Milky Way galaxy about 1,000 light years from Earth in the constellation Perseus. A light year is about 6 trillion miles , the distance light travels in a year.

NASA’s Spitzer Space Telescope enabled them to find quantities of water vapor equal to five times the volume of all the oceans on Earth that had rained down onto a dusty disk around the star where planets are believed to form.

“We’re witnessing the arrival of some future solar system’s supply of water,” astronomer Dan Watson of the University of Rochester in Rochester, New York, who led the research published in the journal Nature, said in a phone interview.

“We think that what we’re seeing in this object now is quite a lot like what our solar system was like at the same age,” Watson added.

Scientists eager to learn whether life exists beyond Earth believe water is one of the key ingredients needed for any life forms.

Water is abundant on Earth and other parts of our solar system, as well as elsewhere in the cosmos, for example, as ice or gas around various stars.


This solar system is forming inside a cocoon of gas and dust, within which is a big disk of planet-forming material.

The observations, made using equipment on the Spitzer Space Telescope called an infrared spectrograph, indicate that icy material from this outer cocoon is in a supersonic free-fall, the scientists said. The ice vaporizes as it reaches the planet-forming disk, they said.

“We 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,” Michael Werner, project scientist for the Spitzer mission at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.

Watson said the Earth’s supply of water was delivered through collisions with icy asteroids and comets. He said the water vapor seen in the distant solar system will freeze again into asteroids and comets.

The star IRAS 4B is extraordinarily young, Watson said.

“It’s probably on the order of thousands to a couple of tens of thousands of years old,” Watson said.

“A star like the sun will live between 10 and 15 billion years, a total life span. Our sun right now is 4.6 billion years old. So this is nothing -- the time it takes for the doctor to pick up the baby,” Watson added.

Right now, IRAS 4B is a lot less massive than the sun, but the scientists said it is too soon to say how big it ultimately will become as it continues to form. “How big the star turns out to be will determine, for example, how big the habitable zone is around it,” Watson said.

The “habitable zone” is the region around a star in which rocky planets like Earth could exist where water would be liquid on the surface and life in theory could take hold.