From: Tony B. Csoka (csoka@itsa.ucsf.edu)
Date: Thu Apr 09 1998 - 19:24:08 MDT
> Astronomers discover a huge chemical "factory" in interstellar space, suggesting origin of
> water in solar system
>
> FOR RELEASE: APRIL 9, 1998
>
> Contact: David Brand
> Office: (607) 255-3651
> E-Mail: deb27@cornell.edu
>
> ITHACA, N.Y. -- A team of U.S. astronomers, led by Cornell University astrophysicist Martin Harwit, has discovered a massive
> concentration of water vapor within a cloud of interstellar gas close to the Orion nebula. The amount of water measured is so high --
> enough to fill the Earth's oceans 60 times a day -- that the researchers believe it provides an important clue to the origin of water in the
> solar system.
>
> The amount of water vapor measured in Orion is 20 times larger than that observed in other interstellar gas clouds in our galaxy, the
> Milky Way. The discovery was made within the Orion molecular cloud, a giant interstellar gas cloud, a trillion miles across, composed
> primarily of hydrogen molecules.
>
> The measurements were made with the long-wavelength spectrometer aboard the Infrared Space Observatory (ISO) launched in
> November 1995 by the European Space Agency with the participation of NASA. The observations were made in October 1997 and are
> reported today (April 20) in the Astrophysical Journal Letters.
>
> Looking in the far-infrared region of the electromagnetic spectrum, the astronomers observed the characteristic signature of emission by
> water vapor. "The interstellar gas cloud that we observed is being pummeled by shock waves that compress and heat the gas," says
> Harwit, who is a Cornell professor emeritus, an ISO mission scientist and lead author on the research report. "These shock waves are
> the result of the violent early stages of star birth in which a young star spews out gas that slams into its surroundings at high speed.
> The heated water vapor that we observed is the result of that collision," he says.
>
> Such a high concentration of water in Orion's giant gas cloud, which swirls around millions of stars along our spiral arm of the Milky
> Way, 1,500 light years from the sun, could have implications for the origin of water in the solar system, says ISO team member David
> Neufeld, professor of physics and astronomy at Johns Hopkins University. "The interstellar gas cloud that we observed in Orion
> seems to be a huge chemical factory generating enough water molecules in a single day to fill the Earth's oceans 60 times over."
>
> Eventually, he says, the water vapor will freeze, becoming small ice particles. Similar ice particles are thought to have been present
> within the gas cloud from which the solar system originally formed. "It seems quite plausible that much of the water in the solar system
> was originally produced in a giant water vapor factory like the one we have observed in Orion," Neufeld says.
>
> Cornell's Harwit speculates that the shock waves observed in the Orion gas cloud could be a cause as well as the result of star birth.
> The shock waves might also trigger the formation of additional stars and planets as they compress the gas cloud -- if the heat can be
> radiated away, says Harwit. "Water vapor is a particularly efficient radiator at far-infrared wavelengths and plays a critical role in
> cooling the gas and facilitating star formation," he notes.
>
> The concentration of water vapor measured by the team was about one part in 2,000 by volume. The new observations confirm
> predictions by astrophysicists over the past 25 years that whenever the temperature exceeds 200 degrees Fahrenheit, chemical reactions
> will convert most of the oxygen atoms in interstellar gas into water.
>
> "An enhanced concentrator of water is precisely what we expected in this gas cloud," says team member Gary Melnick of the
> Harvard-Smithsonian Center for Astrophysics. He adds that the strength of the water radiation detected from Orion was in perfect
> agreement with theoretical predictions published in the doctoral thesis of team member Michael Kaufman, a former Johns Hopkins
> graduate student now at NASA's Ames Research Center.
>
> Panels showing two examples of measurements carried out on board the ISO, together with an image of the Orion nebula taken with
> the Wide Field Planetary Camera 2 on NASA's Hubble Space Telescope, can be seen on the World Wide Web at
> http://www.pha.jhu.edu/~neufeld/orionwater.html.
>
> - 30 -
>
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