[meteorite-list] Herschel Space Observatory Finds Oceans of Water in Planet-Forming Disk Around Nearby Star

[Ron Baalke]

Oct. 20, 2011

Trent J. Perrotto 
Headquarters, Washington 
202-358-0321 
trent.j.perrotto at nasa.gov 

Whitney Clavin 
Jet Propulsion Laboratory, Pasadena, Calif. 
818-354-4673 
whitney.clavin at jpl.nasa.gov 

RELEASE: 11-355

HERSCHEL SPACE OBSERVATORY FINDS OCEANS OF WATER IN PLANET-FORMING DISK AROUND NEARBY STAR

WASHINGTON -- 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. 

The star 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. 

"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. 

For NASA's Herschel website, visit:   

http://www.nasa.gov/herschel 

For ESA's Herschel website, visit:   

http://www.esa.int/SPECIALS/Herschel/index.html 
	
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