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Herschel Finds Oceans of Water in Disk of Nearby Star

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This artist's concept illustrates an icy planet-forming disk around a young star called TW Hydrae, located about 175 light-years away in the Hydra, or Sea Serpent, constellation

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 contributions.

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 through impacts.

“Our 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.

This graph of data from Herschel shows how the cool water vapor was detected.

The star with this waterlogged 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.

“These are 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.

Herschel is a European Space Agency cornerstone mission launched in 2009, carrying science instruments provided by consortia of European institutes. NASA’s Herschel Project Office based at JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. Caltech manages JPL for NASA.
www.nasa.gov

Written by physicsgg

October 20, 2011 at 8:33 pm

Posted in ASTRONOMY, ASTROPHYSICS

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Two Views of a Star’s Exploded Remains

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This layout compares two pictures of a supernova remnant called SN 1987A — the left image was taken by the Herschel Space Observatory, and the right is an enlarged view of the circled region at left, taken with NASA’s Hubble Space Telescope. SN 1987A is the result of a stellar blast that occurred 170,000 light-years away and was seen on Earth in 1987. The tiny pink ring in the Hubble image shows where a shock wave from the blast is hitting the surrounding material expelled from the star before the explosion. The cause for the outer, faint rings is unknown….. Read the rest of this entry »

Written by physicsgg

July 8, 2011 at 1:35 pm

Posted in ASTRONOMY

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