http://www.knoxstudio.com/shns/story.cfm?pk=WATERFROMASTAR-06-21-02&cat=AN - Radio astronomers have discovered rotating jets of water spewing from an ancient, dying star 8,500 light-years from Earth. The corkscrew jets offer some clues, researchers say, about the evolutionary process of stars, and what the ultimate fate of our own star, the sun, may be. It also raises new questions about where the water fueling the jets came from and how it is produced by the dying star. Researchers' findings are being reported in this week's issue of the British science journal Nature. The research team was led by Hiroshi Imai of Japan's National Astronomical Observatory. Using New Mexico's Very Large Array (VLA) and much larger Very Long Baseline Array (VLBA) radio telescopes, the researchers detected radio signals coming from the distant star, known as W43A. The astronomers say W43A is about to become a planetary nebula, a name that is given to dying stars when they collapse, leaving a glowing shell of gas and dust around themselves. Planetary nebulae, despite their name, have nothing to do with planets. Astronomers observing them in the 18th century called them that because of their rounded shapes. For years, astronomers have wondered why planetary nebulae are shaped as they are. "A prime mystery about planetary nebulae is that many are not spherical even though the star from which they are ejected is a sphere," said Philip Diamond, one of the team's researchers, director of the MERLIN radio observatory in Jodrell Bank, England. "The spinning jets of water molecules we found coming from this star," Diamond explained, "may be one mechanism for producing the structures seen in many planetary nebulae." Because the jets are spinning in a spiral away from the star, they cause distortions in its gas shell, the scientists report, and since the jets are only in certain areas, the shell becomes lopsided, making the nebula non-spherical. They conclude that the jets are actually areas around the star that are filled with water molecules that are vibrating in such a way that they amplify the radio signals coming from the star itself. The radio signals cause the jets to emit light waves of a specific frequency, which allowed astronomers to detect and observe them. This effect is known as a maser, which is a radio laser. Lasers work with visible light, while masers work with lower-energy radio waves. While masers can be made in a laboratory, they are a naturally existing phenomenon that are found throughout the universe. What makes these masers special, the team says, is that they are appearing in a planetary nebula. Astronomers have theorized in the past that the odd shapes of planetary nebulae could be a result of such jets, but no jets have ever been observed until now. Nature this week also features a separate commentary on the discovery by VLA radio astronomer Mark Clausen of Socorro, N.M., who said analysis suggests the water jets are only 30 years old. "This strongly suggests that the star has indeed been caught in the act of transition to a planetary nebula," he reports. Clausen writes that Imai and his team used the New Mexico-based telescopes "to determine the distribution of the water masers in the nebula with a precision 200 times greater than that of optical observations by (NASA's orbiting) Hubble Space Telescope." Researchers still don't know what is producing the water jets. xponent Wet 'N' Wild Maru rob
