FOR RELEASE 11 JULY 2001 AT 1:00 PM EDT

STELLAR APOCALYPSE YIELDS FIRST EVIDENCE OF WATER-BEARING WORLDS 
BEYOND OUR SOLAR SYSTEM

As an alien sun blazes through its death throes, it is apparently 
vaporizing a surrounding swarm of comets, releasing a huge cloud of 
water vapor, a team of astronomers reported today. The discovery, 
reported in an article to be published tomorrow in the journal 
Nature, is the result of observations with the Submillimeter Wave 
Astronomy Satellite (SWAS), a small radio observatory that NASA 
launched into  space in December 1998.

The new SWAS observations provide the first evidence that extra-solar 
planetary systems contain water, a molecule that is an essential 
ingredient for known forms of life. This result will be the subject 
of a NASA Space Science Update today at the NASA Headquarters 
auditorium in Washington, D.C., at 1:00 PM.

"Over the past two years, SWAS has detected water vapor from a wide 
variety of astronomical sources," says Dr. Gary Melnick of the 
Harvard-Smithsonian Center for Astrophysics, Principal Investigator 
on the SWAS mission.  "What makes the results we are reporting today 
so unusual is that we have found a cloud of water vapor around a star 
where we would not ordinarily have expected to find water."

The star in question is an aging giant star designated by astronomers 
as IRC+10216, also known as CW Leonis, located 500 light years 
(almost 3,000 trillion miles) from Earth in the direction of the 
constellation Leo.

"IRC+10216 is a carbon-rich star in which the concentration of carbon 
exceeds that of oxygen," explains Melnick.  "In such stars, we expect 
all the oxygen atoms to be bound up in the form of carbon monoxide 
(an oxygen atom and a carbon atom bound together), with almost 
nothing left over to form water (one oxygen atom bound to two 
hydrogen atoms).  Yet we see substantial concentrations of water 
vapor around this star; the most plausible explanation for this water 
vapor is that it is being vaporized from the surfaces of orbiting 
comets, 'dirty snowballs' that are composed primarily of water ice."

From its vantage point in orbit above the absorbing effects of water 
in Earth's atmosphere, SWAS is capable of detecting the distinctive 
radiation emitted by water vapor in space. The observations of water 
vapor around IRC+10216 suggest that other stars may be surrounded by 
planetary systems similar to our own.  Over the past decade, more 
than 50 stars have been shown to have large planets in orbit around 
them, but little is known about the composition of those planets.

In order to explain the water vapor concentration that SWAS has 
detected, several hundred billion comets would be needed at distances 
from the star between 75 and 300 times the distance of the Earth from 
the Sun.  "That sounds like a lot," comments Saavik Ford, a Johns 
Hopkins graduate student who is a co-author on the article reporting 
the discovery.  "But the total mass required of this swarm of 
orbiting comets is similar to the original mass of the Kuiper Belt, a 
collection of comets that orbits our own Sun beyond the orbit of 
Neptune.  In our own solar system, these comets orbit the Sun quietly 
for the most part; occasionally a comet comes in close to the Sun, 
starts to vaporize, and displays the characteristic coma and tail 
that we are familiar with. But IRC+10216 is so much more luminous 
than the Sun that comets start to vaporize even at the distance of 
the Kuiper Belt.  So one has several hundred billion comets all 
vaporizing at once."

The SWAS observations of IRC+10216 paint a picture of the future of 
our solar system.  "We think we are witnessing the type of apocalypse 
that will ultimately befall our own planetary system," says SWAS team 
member Dr. David Neufeld, professor of physics and astronomy at Johns 
Hopkins.  "Several billion years from now, the Sun will become a 
giant star and its power output will increase five thousand fold. As 
the luminosity of the Sun increases, a wave of water vaporization 
will spread outwards through the solar system, starting with Earth's 
oceans and extending well beyond the orbit of Neptune.  Icy bodies as 
large as Pluto will be mostly vaporized, leaving a cinder of hot 
rock."

SWAS was built and operated by NASA with support from the German 
government and the participation of the Harvard-Smithsonian Center 
for Astrophysics, the University of Massachusetts at Amherst, Cornell 
University, the Johns Hopkins University, the University of Cologne, 
Ball Aerospace, and Millitech (now Telaxis Communication Corp.).

In addition to Melnick, Neufeld and Ford, the other co-authors on the 
article reporting the new results on IRC+10216 are Dr. David 
Hollenbach of NASA's Ames Research Center and Dr. Matthew Ashby of 
the Harvard-Smithsonian Center for Astrophysics.