Water-soaked planet-forming region near star seen
US: 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 (10 trillion km), 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.
Washington, Thursday, Reuters |