Finds Star 175 Light-Years From Earth Containing Water
By Shane Nolan
October 24, 2011 - Using data from the Herschel Space Observatory, astronomers have detected for the first time cold water vapor enveloping a dusty disk around a young star.
The findings suggest that this disk, which is poised to
develop into a solar system, contains great quantities
of water, suggesting that water-covered planets like
Earth may be common in the universe. Herschel is a
European Space Agency mission with important NASA
Scientists previously found warm water vapor in
planet-forming disks close to a central star. Evidence
for vast quantities of water extending out into the
cooler, far reaches of disks where comets take shape had
not been seen until now. The more water available in
disks for icy comets to form, the greater the chances
that large amounts eventually will reach new planets
observations of this cold vapor indicate enough water exists in
the disk to fill thousands of Earth oceans," said astronomer
Michiel Hogerheijde of Leiden Observatory in The Netherlands.
Hogerheijde is the lead author of a paper describing these
findings in the Oct. 21 issue of the journal Science.
with this water-logged disk, called TW Hydrae, is 10 million
years old and located about 175 light-years away from Earth, in
the constellation Hydra. The frigid watery haze detected by
Hogerheijde and his team is thought to originate from ice-coated
grains of dust near the disk's surface. Ultraviolet light from
the star causes some water molecules to break free of this ice,
creating a thin layer of gas with a light signature detected by
Herschel's Heterodyne Instrument for the Far-Infrared, or HIFI.
the most sensitive HIFI observations to-date," said Paul
Goldsmith, NASA project scientist for the Herschel Space
Observatory at the agency's Jet Propulsion Laboratory in
Pasadena, Calif. "It is a testament to the instrument-builders
that such weak signals can be detected."
TW Hydrae is an orange dwarf star, somewhat smaller and cooler than our yellow-white sun. The giant disk of material that encircles the star has a size nearly 200 times the distance between Earth and the sun. Over the next few million years, astronomers believe matter within the disk will collide and grow into planets, asteroids and other cosmic bodies. Dust and ice particles will assemble as comets.
As the new solar
system evolves, icy comets are likely to deposit much of the water they
contain on freshly created worlds through impacts, giving rise to
oceans. Astronomers believe TW Hydrae and its icy disk may be
representative of many other young star systems, providing new insights
on how planets with abundant water could form throughout the universe.
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